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  • 151. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    de Plaa, Jelle
    de Vries, Cor P.
    den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguch, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousin, Olivier
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Nobukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, Stephane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sato, Toshiki
    Sawada, Makoto
    Schartel, Norbert
    Serlemtsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shin'ichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shin'ichiro
    Urry, C. Megan
    Ursino, Eugenio
    Watanabe, Shin
    Werner, Norbert
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Tominaga, Nozomu
    Moriya, Takashi J.
    Search for thermal X-ray features from the Crab nebula with the Hitomi soft X-ray spectrometer2018Ingår i: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, nr 2, artikel-id 14Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Crab nebula originated from a core-collapse supernova (SN) explosion observed in 1054 AD. When viewed as a supernova remnant (SNR), it has an anomalously low observed ejecta mass and kinetic energy for an Fe-core-collapse SN. Intensive searches have been made for a massive shell that solves this discrepancy, but none has been detected. An alternative idea is that SN 1054 is an electron-capture (EC) explosion with a lower explosion energy by an order of magnitude than Fe-core-collapse SNe. X-ray imaging searches were performed for the plasma emission from the shell in the Crab outskirts to set a stringent upper limit on the X-ray emitting mass. However, the extreme brightness of the source hampers access to its vicinity. We thus employed spectroscopic technique using the X-ray micro-calorimeter on board the Hitomi satellite. By exploiting its superb energy resolution, we set an upper limit for emission or absorption features from as yet undetected thermal plasma in the 2-12 keV range. We also re-evaluated the existing Chandra and XMM-Newton data. By assembling these results, a new upper limit was obtained for the X-ray plasma mass of less than or similar to 1 M-circle dot for a wide range of assumed shell radius, size, and plasma temperature values both in and out of collisional equilibrium. To compare with the observation, we further performed hydrodynamic simulations of the Crab SNR for two SN models (Fe-core versus EC) under two SN environments (uniform interstellar medium versus progenitor wind). We found that the observed mass limit can be compatible with both SN models if the SN environment has a low density of less than or similar to 0.03 cm(-3) (Fe core) or less than or similar to 0.1 cm(-3) (EC) for the uniform density, or a progenitor wind density somewhat less than that provided by amass loss rate of 10(-5) M-circle dot yr(-1) at 20 km s(-1) for the wind environment.

  • 152. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    de Plaa, Jelle
    de Vries, Cor P.
    den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguchi, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hell, Natalie
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Iwai, Masachika
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousin, Olivier O.
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Norukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, Stephane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sawada, Makoto
    Schartel, Norbert
    Serlemitsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shin'ichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shin'ichiro
    Urry, C. Megan
    Ursino, Eugenio
    Watanabe, Shin
    Werner, Norbert
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Raassen, A. J. J.
    Atomic data and spectral modeling constraints from high-resolution X-ray observations of the Perseus cluster with Hitomi2018Ingår i: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, nr 2, artikel-id 12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Hitomi Soft X-ray Spectrometer spectrum of the Perseus cluster, with similar to 5 eV resolution in the 2-9 keV band, offers an unprecedented benchmark of the atomic modeling and database for hot collisional plasmas. It reveals both successes and challenges of the current atomic data and models. The latest versions of AtomDB/APEC (3.0.8), SPEX (3.03.00), and CHIANTI (8.0) all provide reasonable fits to the broad-band spectrum, and are in close agreement on best-fit temperature, emission measure, and abundances of a few elements such as Ni. For the Fe abundance, the APEC and SPEX measurements differ by 16%, which is 17 times higher than the statistical uncertainty. This is mostly attributed to the differences in adopted collisional excitation and dielectronic recombination rates of the strongest emission lines. We further investigate and compare the sensitivity of the derived physical parameters to the astrophysical source modeling and instrumental effects. The Hitomi results show that accurate atomic data and models are as important as the astrophysical modeling and instrumental calibration aspects. Substantial updates of atomic databases and targeted laboratory measurements are needed to get the current data and models ready for the data from the next Hitomi-level mission.

  • 153. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    de Plaa, Jelle
    de Vries, Cor P.
    den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguchi, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Iwai, Masachika
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousin, Olivier
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Norukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, Stephane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sato, Toshiki
    Sawada, Makoto
    Schartel, Norbert
    Serlemitsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shin'ichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shin'ichiro
    Urry, C. Megan
    Ursino, Eugenio
    Watanabe, Shin
    Werner, Norbert
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Hitomi observations of the LMC SNR N 132 D: Highly redshifted X-ray emission from iron ejecta2018Ingår i: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, nr 2, artikel-id 16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present Hitomi observations of N 132 D, a young, X-ray bright, O-rich core-collapse supernova remnant in the Large Magellanic Cloud (LMC). Despite a very short observation of only 3.7 ks, the Soft X-ray Spectrometer (SXS) easily detects the line complexes of highly ionized S K and Fe K with 16-17 counts in each. The Fe feature is measured for the first time at high spectral resolution. Based on the plausible assumption that the Fe K emission is dominated by He-like ions, we find that the material responsible for this Fe emission is highly redshifted at similar to 800 km s(-1) compared to the local LMC interstellar medium (ISM), with a 90% credible interval of 50-1500 km s(-1) if a weakly informative prior is placed on possible line broadening. This indicates (1) that the Fe emission arises from the supernova ejecta, and (2) that these ejecta are highly asymmetric, since no blueshifted component is found. The S K velocity is consistent with the local LMC ISM, and is likely from swept-up ISM material. These results are consistent with spatial mapping that shows the He-like Fe concentrated in the interior of the remnant and the S tracing the outer shell. The results also show that even with a very small number of counts, direct velocity measurements from Doppler-shifted lines detected in extended objects like supernova remnants are now possible. Thanks to the very low SXS background of similar to 1 event per spectral resolution element per 100 ks, such results are obtainable during short pointed or slew observations with similar instruments. This highlights the power of high-spectral-resolution imaging observations, and demonstrates the new window that has been opened with Hitomi and will be greatly widened with future missions such as the X-ray Astronomy Recovery Mission (XARM) and Athena.

  • 154. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    De Plaa, Jelle
    De Vries, Cor P.
    Den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguchi, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Iwai, Masachika
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousin, Olivier O.
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Nobukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Oshimizu, Kenya
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, Stephane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sawada, Makoto
    Schartel, Norbert
    Serlemtsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shinichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shinichiro
    Urry, C. Megan
    Ursino, Eugenio
    Watanabe, Shin
    Werner, Norbert
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Terasawa, Toshio
    Sekido, Mamoru
    Takefuji, Kazuhiro
    Kawai, Eiji
    Misawa, Hiroaki
    Tsuchiya, Fuminori
    Yamazaki, Ryo
    Kobayashi, Eiji
    Kisaka, Shota
    Aoki, Takahiro
    Hitomi X-ray studies of giant radio pulses from the Crab pulsar2018Ingår i: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, nr 2, artikel-id 15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 sigma fluctuations of the X-ray fluxes at the pulse peaks, and the 3 sigma upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2-300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and 70-300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) x 10(-11) erg cm(-2), respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magneto-sphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a > 0.02% brightening of the pulse-peak flux under such conditions.

  • 155. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    de Plaa, Jelle
    de Vries, Cor P.
    den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguchi, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Iwai, Masachika
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousin, Olivier O.
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Norukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, Stephane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sawada, Makoto
    Schartel, Norbert
    Serlemitsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shin'ichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shin'ichiro
    Urry, C. Megan
    Ursino, Eugenio
    Watanabe, Shin
    Werner, Norbert
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Kawamuro, Taiki
    Hitomi observation of radio galaxy NGC 1275: The first X-ray microcalorimeter spectroscopy of Fe-K alpha line emission from an active galactic nucleus2018Ingår i: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, nr 2, artikel-id 13Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin of the narrow Fe-K alpha fluorescence line at 6.4 keV from active galactic nuclei has long been under debate; some of the possible sites are the outer accretion disk, the broad line region, a molecular torus, or interstellar/intracluster media. In 2016 February-March, we performed the first X-ray microcalorimeter spectroscopy with the Soft X-ray Spectrometer (SXS) on board the Hitomi satellite of the Fanaroff-Riley type I radio galaxy NGC 1275 at the center of the Perseus cluster of galaxies. With the high-energy resolution of similar to 5 eV at 6 keV achieved by Hitomi/SXS, we detected the Fe-K alpha line with similar to 5.4 sigma significance. The velocity width is constrained to be 500-1600 km s(-1) (FWHM for Gaussian models) at 90% confidence. The SXS also constrains the continuum level from the NGC 1275 nucleus up to similar to 20 keV, giving an equivalent width of similar to 20 eV for the 6.4 keV line. Because the velocity width is narrower than that of the broad H alpha line of similar to 2750 km s(-1), we can exclude a large contribution to the line flux from the accretion disk and the broad line region. Furthermore, we performed pixel map analyses on the Hitomi/SXS data and image analyses on the Chandra archival data, and revealed that the Fe-K alpha line comes from a region within similar to 1.6 kpc of the NGC 1275 core, where an active galactic nucleus emission dominates, rather than that from intracluster media. Therefore, we suggest that the source of the Fe-K alpha line from NGC 1275 is likely a low-covering-fraction molecular torus or a rotating molecular disk which probably extends from a parsec to hundreds of parsecs scale in the active galactic nucleus system.

  • 156. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    de Plaa, Jelle
    de Vries, Cor P.
    den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguchi, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Iwai, Masachika
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousin, Olivier O.
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Norukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, Stephane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sawada, Makoto
    Schartel, Norbert
    Serlemitsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shinichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shinichiro
    Urry, C. Megan
    Ursino, Eugenio
    Watanabe, Shin
    Werner, Norbert
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Nakaniwa, Nozomi
    Glimpse of the highly obscured HMXB IGR J16318-4848 with Hitomi2018Ingår i: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, nr 2, artikel-id 17Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a Hitomi observation of IGR J16318-4848, a high-mass X-ray binary system with an extremely strong absorption of N-H similar to 10(24) cm(-2). Previous X-ray studies revealed that its spectrum is dominated by strong fluorescence lines of Fe as well as continuum emission lines. For physical and geometrical insight into the nature of the reprocessing material, we utilized the high spectroscopic resolving power of the X-ray microcalorimeter (the soft X-ray spectrometer: SXS) and the wide-band sensitivity by the soft and hard X-ray imagers (SXI and HXI) aboard Hitomi. Even though the photon counts are limited due to unintended off-axis pointing, the SXS spectrum resolves Fe K alpha(1) and K alpha(2) lines and puts strong constraints on the line centroid and line width. The line width corresponds to a velocity of 160(-70)(+300) km s(-1). This represents the most accurate, and smallest, width measurement of this line made so far from the any X-ray binary, much less than the Doppler broadening and Doppler shift expected from speeds that are characteristic of similar systems. Combined with the K-shell edge energy measured by the SXI and HXI spectra, the ionization state of Fe is estimated to be in the range of Fe I-IV. Considering the estimated ionization parameter and the distance between the X-ray source and the absorber, the density and thickness of the materials are estimated. The extraordinarily strong absorption and the absence of a Compton shoulder component have been confirmed. These characteristics suggest reprocessing materials that are distributed in a narrow solid angle or scattering, primarily by warm free electrons or neutral hydrogen. This measurement was achieved using the SXS detection of 19 photons. It provides strong motivation for follow-up observations of this and other X-ray binaries using the X-ray Astrophysics Recovery Mission and other comparable future instruments.

  • 157. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory V.
    Bulbul, Esra
    Cackett, Edward M.
    Chernyakova, Maria
    Chiao, Meng P.
    Coppi, Paolo S.
    Costantini, Elisa
    De Plaa, Jelle
    den Herder, Jan-Willem
    Done, Chris
    Dotani, Tadayasu
    Ebisawa, Ken
    Eckart, Megan E.
    Enoto, Teruaki
    Ezoe, Yuichiro
    Fabian, Andrew C.
    Ferrigno, Carlo
    Foster, Adam R.
    Fujimoto, Ryuichi
    Fukazawa, Yasushi
    Furuzawa, Akihiro
    Galeazzi, Massimiliano
    Gallo, Luigi C.
    Gandhi, Poshak
    Giustini, Margherita
    Goldwurm, Andrea
    Gu, Liyi
    Guainazzi, Matteo
    Haba, Yoshito
    Hagino, Kouichi
    Hamaguchi, Kenji
    Harrus, Ilana M.
    Hatsukade, Isamu
    Hayashi, Katsuhiro
    Hayashi, Takayuki
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Yoshiyuki
    Ishida, Manabu
    Ishikawa, Kumi
    Ishisaki, Yoshitaka
    Iwai, Masachika
    Kaastra, Jelle
    Kallman, Tim
    Kamae, Tsuneyoshi
    Kataoka, Jun
    Katsuda, Satoru
    Kawai, Nobuyuki
    Kelley, Richard L.
    Kilbourne, Caroline A.
    Kitaguchi, Takao
    Kitamoto, Shunji
    Kitayama, Tetsu
    Kohmura, Takayoshi
    Kokubun, Motohide
    Koyama, Katsuji
    Koyama, Shu
    Kretschmar, Peter
    Krimm, Hans A.
    Kubota, Aya
    Kunieda, Hideyo
    Laurent, Philippe
    Lee, Shiu-Hang
    Leutenegger, Maurice A.
    Limousine, Olivier
    Loewenstein, Michael
    Long, Knox S.
    Lumb, David
    Madejski, Greg
    Maeda, Yoshitomo
    Maier, Daniel
    Makishima, Kazuo
    Markevitch, Maxim
    Matsumoto, Hironori
    Matsushita, Kyoko
    McCammon, Dan
    McNamara, Brian R.
    Mehdipour, Missagh
    Miller, Eric D.
    Miller, Jon M.
    Mineshige, Shin
    Mitsuda, Kazuhisa
    Mitsuishi, Ikuyuki
    Miyazawa, Takuya
    Mizuno, Tsunefumi
    Mori, Hideyuki
    Mori, Koji
    Mukai, Koji
    Murakami, Hiroshi
    Mushotzky, Richard F.
    Nakagawa, Takao
    Nakajima, Hiroshi
    Nakamori, Takeshi
    Nakashima, Shinya
    Nakazawa, Kazuhiro
    Nobukawa, Kumiko K.
    Nobukawa, Masayoshi
    Noda, Hirofumi
    Odaka, Hirokazu
    Ohashi, Takaya
    Ohno, Masanori
    Okajima, Takashi
    Ota, Naomi
    Ozaki, Masanobu
    Paerels, Frits
    Paltani, StPhane
    Petre, Robert
    Pinto, Ciro
    Porter, Frederick S.
    Pottschmidt, Katja
    Reynolds, Christopher S.
    Safi-Harb, Samar
    Saito, Shinya
    Sakai, Kazuhiro
    Sasaki, Toru
    Sato, Goro
    Sato, Kosuke
    Sato, Rie
    Sawada, Makoto
    Schartel, Norbert
    Serlemitsos, Peter J.
    Seta, Hiromi
    Shidatsu, Megumi
    Simionescu, Aurora
    Smith, Randall K.
    Soong, Yang
    Stawarz, Lukasz
    Sugawara, Yasuharu
    Sugita, Satoshi
    Szymkowiak, Andrew
    Tajima, Hiroyasu
    Takahashi, Hiromitsu
    Takahashi, Tadayuki
    Takeda, Shin'ichiro
    Takei, Yoh
    Tamagawa, Toru
    Tamura, Takayuki
    Tanaka, Takaaki
    Tanaka, Yasuo
    Tanaka, Yasuyuki T.
    Tashiro, Makoto S.
    Tawara, Yuzuru
    Terada, Yukikatsu
    Terashima, Yuichi
    Tombesi, Francesco
    Tomida, Hiroshi
    Tsuboi, Yohko
    Tsujimoto, Masahiro
    Tsunemi, Hiroshi
    Tsuru, Takeshi Go
    Uchida, Hiroyuki
    Uchiyama, Hideki
    Uchiyama, Yasunobu
    Ueda, Shutaro
    Ueda, Yoshihiro
    Uno, Shin'ichiro
    Urry, C. Megan
    Ursino, Eugenio
    de Vries, Cor P.
    Watanabe, Shin
    Werner, Norbert
    Wik, Daniel R.
    Wilkins, Dan R.
    Williams, Brian J.
    Yamada, Shinya
    Yamaguchi, Hiroya
    Yamaoka, Kazutaka
    Yamasaki, Noriko Y.
    Yamauchi, Makoto
    Yamauchi, Shigeo
    Yaqoob, Tahir
    Yatsu, Yoichi
    Yonetoku, Daisuke
    Zhuravleva, Irina
    Zoghbi, Abderahmen
    Solar abundance ratios of the iron-peak elements in the Perseus cluster2017Ingår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 551, nr 7681, s. 478-+Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The metal abundance of the hot plasma that permeates galaxy clusters represents the accumulation of heavy elements produced by billions of supernovae(1). Therefore, X-ray spectroscopy of the intracluster medium provides an opportunity to investigate the nature of supernova explosions integrated over cosmic time. In particular, the abundance of the iron-peak elements (chromium, manganese, iron and nickel) is key to understanding how the progenitors of typical type Ia supernovae evolve and explode(2-6). Recent X-ray studies of the intracluster medium found that the abundance ratios of these elements differ substantially from those seen in the Sun(7-11), suggesting differences between the nature of type Ia supernovae in the clusters and in the Milky Way. However, because the K-shell transition lines of chromium and manganese are weak and those of iron and nickel are very close in photon energy, highresolution spectroscopy is required for an accurate determination of the abundances of these elements. Here we report observations of the Perseus cluster, with statistically significant detections of the resonance emission from chromium, manganese and nickel. Our measurements, combined with the latest atomic models, reveal that these elements have near-solar abundance ratios with respect to iron, in contrast to previous claims. Comparison between our results and modern nucleosynthesis calculations(12-14) disfavours the hypothesis that type Ia supernova progenitors are exclusively white dwarfs with masses well below the Chandrasekhar limit (about 1.4 times the mass of the Sun). The observed abundance pattern of the iron-peak elements can be explained by taking into account a combination of near-and sub-Chandrasekhar-mass type Ia supernova systems, adding to the mounting evidence that both progenitor types make a substantial contribution to cosmic chemical enrichment(5,15,16).

  • 158. Ahn, Kyungjin
    et al.
    Iliev, Ilian T.
    Shapiro, Paul R.
    Mellema, Garrelt
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Koda, Jun
    Mao, Yi
    DETECTING THE RISE AND FALL OF THE FIRST STARS BY THEIR IMPACT ON COSMIC REIONIZATION2012Ingår i: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 756, nr 1, s. L16-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The intergalactic medium was reionized before redshift z similar to 6, most likely by starlight which escaped from early galaxies. The very first stars formed when hydrogen molecules (H-2) cooled gas inside the smallest galaxies, minihalos (MHs) of mass between 10(5) and 10(8) M-circle dot. Although the very first stars began forming inside these MHs before redshift z similar to 40, their contribution has, to date, been ignored in large-scale simulations of this cosmic reionization. Here we report results from the first reionization simulations to include these first stars and the radiative feedback that limited their formation, in a volume large enough to follow the crucial spatial variations that influenced the process and its observability. We show that, while MH stars stopped far short of fully ionizing the universe, reionization began much earlier with MH sources than without, and was greatly extended, which boosts the intergalactic electron-scattering optical depth and the large-angle polarization fluctuations of the cosmic microwave background significantly. This boost should be readily detectable by Planck, although within current Wilkinson Microwave Anisotropy Probe uncertainties. If reionization ended as late as z(ov) less than or similar to 7, as suggested by other observations, Planck will thereby see the signature of the first stars at high redshift, currently undetectable by other probes.

  • 159. Ahn, Kyungjin
    et al.
    Shapiro, Paul R.
    Iliev, Ilian T.
    Mellema, Garrelt
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Pen, Ue-Li
    The Inhomogeneous Background Of H2-Dissociating Radiation During Cosmic Reionization2009Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 695, s. 1430-1445Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The first, self-consistent calculations are presented of the cosmological, H2-dissociating UV background produced during the epoch of reionization by the sources of reionization. Large-scale radiative transfer simulations of reionization trace the impact of all the ionizing starlight on the intergalactic medium (IGM) from all the sources in our simulation volume down to dwarf galaxies of mass ~108 M sun, identified by very high resolution N-body simulations, including the self-regulating effect of IGM photoheating on dwarf galaxy formation. The UV continuum emitted below 13.6 eV by each source is then transferred through the same IGM, attenuated by atomic H Lyman series resonance lines, to predict the evolution of the inhomogeneous radiation background in the Lyman-Werner (LW) bands of H2 between 11 and 13.6 eV. On average, the intensity of this LW background is found to rise to the threshold level at which dissociation suppresses H2 cooling and star formation inside minihalos, long before reionization is complete. Spatial variations in the LW background are found which result from the clustering of sources associated with large-scale structure formation, such that intensity fluctuations correlate with matter density fluctuations. As a result, the LW background rises to the threshold level for H2 suppression earlier in the vicinity of the reionization sources and their H II regions.

  • 160. Ahnen, M. L.
    et al.
    Ansoldi, S.
    Antonelli, L. A.
    Antoranz, P.
    Babic, A.
    Banerjee, B.
    Bangale, P.
    Barres de Almeida, U.
    Barrio, J. A.
    Gonzalez, J. Becerra
    Bednarek, W.
    Bernardinik, E.
    Biasuzzi, B.
    Biland, A.
    Blanch, O.
    Bonnefoy, S.
    Bonnoli, G.
    Borracci, F.
    Bretz, T.
    Carmona, E.
    Carosi, A.
    Chatterjee, A.
    Clavero, R.
    Colin, P.
    Colombo, E.
    Contreras, J. L.
    Cortina, J.
    Covino, S.
    Da Vela, P.
    Dazzi, F.
    De Angelis, A.
    De Lotto, B.
    De Ona Wilhelmi, E.
    Delgado Mendez, C.
    Di Pierro, F.
    Dominis Prester, D.
    Dorner, D.
    Doro, M.
    Einecke, S.
    Eisenacher Glawion, D.
    Elsaesser, D.
    Fernandez-Barral, A.
    Fidalgo, D.
    Fonseca, M. V.
    Font, L.
    Frantzen, K.
    Fruck, C.
    Galindo, D.
    Garcia Lopez, R. J.
    Garczarczyk, M.
    Garrido Terrats, D.
    Gaug, M.
    Giammaria, P.
    Godinovic, N.
    Gonzalez Munoz, A.
    Guberman, D.
    Hahn, A.
    Hanabata, Y.
    Hayashida, M.
    Herrera, J.
    Hose, J.
    Hrupec, D.
    Hughes, G.
    Idec, W.
    Kodani, K.
    Konno, Y.
    Kubo, H.
    Kushida, J.
    La Barbera, A.
    Lelas, D.
    Lindfors, E.
    Lombardi, S.
    Longo, F.
    Lopez, M.
    Lopez-Coto, R.
    Lopez-Dramas, A.
    Lorenz, E.
    Majumdar, P.
    Makariev, M.
    Mallot, K.
    Maneva, G.
    Manganaro, M.
    Mannheim, K.
    Maraschi, L.
    Marcote, B.
    Mariotti, M.
    Martinez, M.
    Mazing, D.
    Menzel, U.
    Miranda, J. M.
    Mirzoyan, R.
    Moralejo, A.
    Moretti, E.
    Nakajima, D.
    Neustroev, V.
    Niedzwiecki, A.
    Nievas Rosillo, M.
    Nilsson, K.
    Nishijima, K.
    Noda, K.
    Orito, R.
    Overkemping, A.
    Paiano, S.
    Palacio, J.
    Palatiello, M.
    Paneque, D.
    Paoletti, R.
    Paredes, J. M.
    Paredes-Fortuny, X.
    Persic, M.
    Poutanen, J.
    Prada Moroni, P. G.
    Prandini, E.
    Puljak, I.
    Rhode, W.
    Ribo, M.
    Rico, J.
    Rodriguez Garcia, J.
    Saito, T.
    Satalecka, K.
    Schultz, C.
    Schweizer, T.
    Shore, S. N.
    Sillanpaa, A.
    Sitarek, J.
    Snidaric, I.
    Sobczynska, D.
    Stamerra, A.
    Steinbring, T.
    Strzys, M.
    Takalo, L.
    Takami, H.
    Tavecchio, F.
    Temnikov, P.
    Terzic, T.
    Tescaro, D.
    Teshimag, M.
    Thaele, J.
    Torres, D. F.
    Toyama, T.
    Treves, A.
    Verguilov, V.
    Vovk, I.
    Ward, J. E.
    Will, M.
    Wu, M. H.
    Zanins, R.
    Aleksic, J.
    Wood, M.
    Anderson, Brandon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bloom, E. D.
    Cohen-Tanugi, J.
    Drlica-Wagner, A.
    Mazziotta, M. N.
    Sanchez-Conde, Miguel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Strigari, L.
    Limits to dark matter annihilation cross-section from a combined analysis of MAGIC and Fermi-LAT observations of dwarf satellite galaxies2016Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 2, artikel-id 039Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the first joint analysis of gamma-ray data from the MAGIC Cherenkov telescopes and the Fermi Large Area Telescope (LAT) to search for gamma-ray signals from dark matter annihilation in dwarf satellite galaxies. We combine 158 hours of Segue 1 observations with MAGIC with 6-year observations of 15 dwarf satellite galaxies by the Fermi-LAT. We obtain limits on the annihilation cross-section for dark matter particle masses between 10 GeV and 100 TeV - the widest mass range ever explored by a single gamma-ray analysis. These limits improve on previously published Fermi-LAT and MAGIC results by up to a factor of two at certain masses. Our new inclusive analysis approach is completely generic and can be used to perform a global, sensitivity-optimized dark matter search by combining data from present and future gamma-ray and neutrino detectors.

  • 161.
    Ahrens, Maryon
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Investigating the potential of current and future neutrino detectors to identify the sources of the astrophysical neutrinos seen by IceCube2018Licentiatavhandling, monografi (Övrigt vetenskapligt)
    Abstract [sv]

    Målet med neutrinoastronomi är att betrakta vårt universum med en ny budbärare, neutrinon. Denna budbärare erbjuder ett fönster mot universum som komplementerar den bild vi får från fotoner, kosmisk strålning och gravitationsvågor. Genom att använda flera budbärare erhåller vi en mer enhetlig bild av vårt universum.

    Ett flöde av astrofysikaliska neutriner observerades nyligen av den på sydpolen belägna neutrinodetektorn IceCube, men ursprunget till dessa neutriner har ännu inte helt klarlagts. Eftersom neutriner kan färdas mycket långa sträckor, utgörs en extragalaktisk komponent troligtvis av neutrinor från mycket avlägsna och svaga källor. Detta försvårar utsikterna att kunna identifiera enskilda astrofysikaliska neutrinokällor.

    Denna avhandling utforskar de krav som olika klasser av neutrinokällor ställer på en generisk neutrino detektor, för att en sådan ska kunna upplösa enskilda neutrinokällor, samt undersöker vilka klasser av neutrinokällor vi kan ha hopp om att kunna identifiera med nuvarande och framtida detektorer.

    Utifall det astrofysikaliska flödet domineras av neutriner från galaxer med förstärkt stjärnbildning ("starburst galaxies") är identifikation förmodligen svårt. Däremot finns det gott hopp om att kunna identifiera neutriner från de väldigt ljusstarka centrala regionerna som man finner i vissa galaxer ("active galactic nuclei" samt "blazars"), antingen med IceCube eller nästa generations neutrino detektorer, som IceCube Gen2.

  • 162.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Danninger, Matthias
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Atmospheric and astrophysical neutrinos above 1 TeV interacting in IceCube2015Ingår i: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, nr 2, s. 022001-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The IceCube Neutrino Observatory was designed primarily to search for high-energy (TeV-PeV) neutLrinos produced in distant astrophysical objects. A search for. greater than or similar to 100 TeV neutrinos interacting inside the instrumented volume has recently provided evidence for an isotropic flux of such neutrinos. At lower energies, IceCube collects large numbers of neutrinos from the weak decays of mesons in cosmic-ray air showers. Here we present the results of a search for neutrino interactions inside IceCube's instrumented volume between 1 TeV and 1 PeV in 641 days of data taken from 2010-2012, lowering the energy threshold for neutrinos from the southern sky below 10 TeV for the first time, far below the threshold of the previous high-energy analysis. Astrophysical neutrinos remain the dominant component in the southern sky down to a deposited energy of 10 TeV. From these data we derive new constraints on the diffuse astrophysical neutrino spectrum, Phi(v) = 2.06(-0.3)(+0.4) x 10(-18) (E-v = 10(5) GeV)-2.46 +/- 0.12GeV-1 cm(-2) sr(-1) s(-1) for 25 TeV < E-v < 1.4 PeV, as well as the strongest upper limit yet on the flux of neutrinos from charmed-meson decay in the atmosphere, 1.52 times the benchmark theoretical prediction used in previous IceCube results at 90% confidence.

  • 163.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    A COMBINED MAXIMUM-LIKELIHOOD ANALYSIS OF THE HIGH-ENERGY ASTROPHYSICAL NEUTRINO FLUX MEASURED WITH ICECUBE2015Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 809, nr 1, artikel-id 98Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Evidence for an extraterrestrial flux of high-energy neutrinos has now been found in multiple searches with the IceCube detector. The first solid evidence was provided by a search for neutrino events with deposited energies greater than or similar to 30 TeV and interaction vertices inside the instrumented volume. Recent analyses suggest that the extraterrestrial flux extends to lower energies and is also visible with throughgoing, nu(mu)-induced tracks from the Northern Hemisphere. Here, we combine the results from six different IceCube searches for astrophysical neutrinos in a maximum-likelihood analysis. The combined event sample features high-statistics samples of shower-like and track-like events. The data are fit in up to three observables: energy, zenith angle, and event topology. Assuming the astrophysical neutrino flux to be isotropic and to consist of equal flavors at Earth, the all-flavor spectrum with neutrino energies between 25 TeV and 2.8 PeV is well described by an unbroken power law with best-fit spectral index -2.50 +/- 0.09 and a flux at 100 TeV of (6.7(-1.2)(+1.1)) x 10(-18) GeV-1 s(-1) sr(-1) cm(-2). Under the same assumptions, an unbroken power law with index -2 is disfavored with a significance of 3.8 sigma (p = 0.0066%) with respect to the best fit. This significance is reduced to 2.1 sigma (p = 1.7%) if instead we compare the best fit to a spectrum with index -2 that has an exponential cut-off at high energies. Allowing the electron-neutrino flux to deviate from the other two flavors, we find a nu(e) fraction of 0.18 +/- 0.11 at Earth. The sole production of electron neutrinos, which would be characteristic of neutron-decay-dominated sources, is rejected with a significance of 3.6 sigma ( p = 0.014%).

  • 164.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    ANISOTROPY IN COSMIC-RAY ARRIVAL DIRECTIONS IN THE SOUTHERN HEMISPHERE BASED ON SIX YEARS OF DATA FROM THE ICECUBE DETECTOR2016Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 826, nr 2, artikel-id 220Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The IceCube Neutrino Observatory accumulated a total of 318 billion cosmic-ray-induced muon events between 2009 May and 2015 May. This data set was used for a detailed analysis of the sidereal anisotropy in the arrival directions of cosmic rays in the TeV to PeV energy range. The observed global sidereal anisotropy features large regions of relative excess and deficit, with amplitudes of the order of 10(-3) up to about 100 TeV. A decomposition of the arrival direction distribution into spherical harmonics shows that most of the power is contained in the low-multipole (l <= 4) moments. However, higher multipole components are found to be statistically significant down to an angular scale of less than 10 degrees, approaching the angular resolution of the detector. Above 100 TeV, a change in the morphology of the arrival direction distribution is observed, and the anisotropy is characterized by a wide relative deficit whose amplitude increases with primary energy up to at least 5 PeV, the highest energies currently accessible to IceCube. No time dependence of the large-and small-scale structures is observed in the period of six years covered by this analysis. The high-statistics data set reveals more details of the properties of the anisotropy and is potentially able to shed light on the various physical processes that are responsible for the complex angular structure and energy evolution.

  • 165.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Characterization of the atmospheric muon flux in IceCube2016Ingår i: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 78, s. 1-27Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Muons produced in atmospheric cosmic ray showers account for the by far dominant part of the event yield in large-volume underground particle detectors. The IceCube detector, with an instrumented volume of about a cubic kilometer, has the potential to conduct unique investigations on atmospheric muons by exploiting the large collection area and the possibility to track particles over a long distance. Through detailed reconstruction of energy deposition along the tracks, the characteristics of muon bundles can be quantified, and individual particles of exceptionally high energy identified. The data can then be used to constrain the cosmic ray primary flux and the contribution to atmospheric lepton fluxes from prompt decays of short-lived hadrons. In this paper, techniques for the extraction of physical measurements from atmospheric muon events are described and first results are presented. The multiplicity spectrum of TeV muons in cosmic ray air showers for primaries in the energy range from the knee to the ankle is derived and found to be consistent with recent results from surface detectors. The single muon energy spectrum is determined up to PeV energies and shows a clear indication for the emergence of a distinct spectral component from prompt decays of short-lived hadrons. The magnitude of the prompt flux, which should include a substantial contribution from light vector meson di-muon decays, is consistent with current theoretical predictions. The variety of measurements and high event statistics can also be exploited for the evaluation of systematic effects. In the course of this study, internal inconsistencies in the zenith angle distribution of events were found which indicate the presence of an unexplained effect outside the currently applied range of detector systematics. The underlying cause could be related to the hadronic interaction models used to describe muon production in air showers.

  • 166.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    THE FIRST COMBINED SEARCH FOR NEUTRINO POINT-SOURCES IN THE SOUTHERN HEMISPHERE WITH THE ANTARES AND ICECUBE NEUTRINO TELESCOPES2016Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 823, nr 1, artikel-id 65Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the results of searches for point-like sources of neutrinos based on the first combined analysis of data from both the ANTARES and IceCube neutrino telescopes. The combination of both detectors, which differ in size and location, forms a window in the southern sky where the sensitivity to point sources improves by up to a factor of 2 compared with individual analyses. Using data recorded by ANTARES from 2007 to 2012, and by IceCube from 2008 to 2011, we search for sources of neutrino emission both across the southern sky and from a preselected list of candidate objects. No significant excess over background has been found in these searches, and flux upper limits for the candidate sources are presented for E-2.5 and E-2 power-law spectra with different energy cut-offs.

  • 167.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hulth, Per Olof
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    THE SEARCH FOR TRANSIENT ASTROPHYSICAL NEUTRINO EMISSION WITH ICECUBE-DEEPCORE2016Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 816, nr 2, artikel-id 75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the results of a search for astrophysical sources of brief transient neutrino emission using IceCube and DeepCore data acquired between 2012 May 15 and 2013 April 30. While the search methods employed in this analysis are similar to those used in previous IceCube point source searches, the data set being examined consists of a sample of predominantly sub-TeV muon-neutrinos from the Northern Sky (-5 degrees < delta < 90 degrees) obtained through a novel event selection method. This search represents a first attempt by IceCube to identify astrophysical neutrino sources in this relatively unexplored energy range. The reconstructed direction and time of arrival of neutrino events are used to search for any significant self-correlation in the data set. The data revealed no significant source of transient neutrino emission. This result has been used to construct limits at timescales ranging from roughly 1 s to 10 days for generic soft-spectra transients. We also present limits on a specific model of neutrino emission from soft jets in core-collapse supernovae.

  • 168.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    OBSERVATION AND CHARACTERIZATION OF A COSMIC MUON NEUTRINO FLUX FROM THE NORTHERN HEMISPHERE USING SIX YEARS OF ICECUBE DATA2016Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 833, nr 1, artikel-id 3Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The IceCube Collaboration has previously discovered a high-energy astrophysical neutrino flux using neutrino events with interaction vertices contained within the instrumented volume of the IceCube detector. We present a complementary measurement using charged current muon neutrino events where the interaction vertex can be outside this volume. As a consequence of the large muon range the effective area is significantly larger but the field of view is restricted to the Northern Hemisphere. IceCube data from 2009 through 2015 have been analyzed using a likelihood approach based on the reconstructed muon energy and zenith angle. At the highest neutrino energies between 194 TeV and 7.8 PeV a significant astrophysical contribution is observed, excluding a purely atmospheric origin of these events at 5.6 sigma significance. The data are well described by an isotropic, unbroken power-law flux with a normalization at 100 TeV neutrino energy of (0.90(-0.27)(+0.30)) x 10(-18) GeV-1 cm(-2) s(-1) sr(-1) and a hard spectral index of gamma = 2.13 +/- 0.13. The observed spectrum is harder in comparison to previous IceCube analyses with lower energy thresholds which may indicate a break in the astrophysical neutrino spectrum of unknown origin. The highest-energy event observed has a reconstructed muon energy of (4.5 +/- 1.2) PeV which implies a probability of less than 0.005% for this event to be of atmospheric origin. Analyzing the arrival directions of all events with reconstructed muon energies above 200 TeV no correlation with known gamma-ray sources was found. Using the high statistics of atmospheric neutrinos we report the current best constraints on a prompt atmospheric muon neutrino flux originating from charmed meson decays which is below 1.06 in units of the flux normalization of the model in Enberg et al.

  • 169.
    Ahrens, Maryon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Bohm, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Dumm, Jonathan P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Finley, Chad
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Flis, Samuel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Hultqvist, Klas
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Walck, Christian
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wolf, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zoll, Marcel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    SEARCH FOR SOURCES OF HIGH-ENERGY NEUTRONS WITH FOUR YEARS OF DATA FROM THE ICETOP DETECTOR2016Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 830, nr 2, artikel-id 129Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    IceTop is an air-shower array located on the Antarctic ice sheet at the geographic South Pole. IceTop can detect an astrophysical flux of neutrons from Galactic sources as an excess of cosmic-ray air showers arriving from the source direction. Neutrons are undeflected by the Galactic magnetic field and can typically travel 10 (E/PeV) pc before decay. Two searches are performed using 4 yr of the IceTop data set to look for a statistically significant excess of events with energies above 10 PeV (10(16) eV) arriving within a small solid angle. The all-sky search method covers from -90 degrees to approximately -50 degrees in declination. No significant excess is found. A targeted search is also performed, looking for significant correlation with candidate sources in different target sets. This search uses a higher-energy cut (100 PeV) since most target objects lie beyond 1 kpc. The target sets include pulsars with confirmed TeV energy photon fluxes and high-mass X-ray binaries. No significant correlation is found for any target set. Flux upper limits are determined for both searches, which can constrain Galactic neutron sources and production scenarios.

  • 170. Ajello, M.
    et al.
    Albert, A.
    Allafort, A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Bonamente, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Palma, F.
    Dermer, C. D.
    Desiante, R.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    Jackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Knoedlseder, J.
    Kocevski, D.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Murphy, R.
    Nakamori, T.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Roth, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, D. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    IMPULSIVE AND LONG DURATION HIGH-ENERGY GAMMA-RAY EMISSION FROM THE VERY BRIGHT 2012 MARCH 7 SOLAR FLARES2014Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 789, nr 1, s. 20-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Fermi Large Area Telescope (LAT) detected gamma-rays up to 4 GeV from two bright X-class solar flares on 2012 March 7, showing both an impulsive and temporally extended emission phases. The gamma-rays appear to originate from the same active region as the X-rays associated with these flares. The >100 MeV gamma-ray flux decreases monotonically during the first hour (impulsive phase) followed by a slower decrease for the next 20 hr. A power law with a high-energy exponential cutoff can adequately describe the photon spectrum. Assuming that the gamma rays result from the decay of pions produced by accelerated protons and ions with a power-law spectrum, we find that the index of that spectrum is similar to 3, with minor variations during the impulsive phase. During the extended phase the photon spectrum softens monotonically, requiring the proton index varying from similar to 4 to >5. The >30 MeV proton flux observed by the GOES satellites also shows a flux decrease and spectral softening, but with a harder spectrum (index similar to 2-3). Based on these observations, we explore the relative merits of prompt or continuous acceleration scenarios, hadronic or leptonic emission processes, and acceleration at the solar corona or by the fast coronal mass ejections. We conclude that the most likely scenario is continuous acceleration of protons in the solar corona that penetrate the lower solar atmosphere and produce pions that decay into gamma rays. However, acceleration in the downstream of the shock cannot be definitely ruled out.

  • 171. Ajello, M.
    et al.
    Albert, A.
    Atwood, W. B.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Carave, P. A.
    Cecchi, C.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Di Venere, L.
    Drell, P. S.
    Favuzzi, C.
    Ferrara, E. C.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Guiriec, S.
    Gustafsson, M.
    Harding, A. K.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Karwin, C.
    Knoedlseder, J.
    Kuss, M.
    Larsson, Stefan
    Latronico, L.
    Li, J.
    Li, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Magill, J.
    Maldera, S.
    Malyshev, D.
    Manfreda, A.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Sanchez-Conde, Miguel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Parkinson, P. M. Saz
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Thayer, J. B.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Winer, B. L.
    Wood, K. S.
    Zaharijas, G.
    Zimmer, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    FERMI-LAT OBSERVATIONS OF HIGH-ENERGY gamma-RAY EMISSION TOWARD THE GALACTIC CENTER2016Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 819, nr 1, artikel-id 44Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Fermi Large Area Telescope (LAT) has provided the most detailed view to date of the emission toward the Galactic center (GC) in high-energy gamma-rays. This paper describes the analysis of data taken during the first 62 months of the mission in the energy range 1-100 GeV from a 15 degrees x 15 degrees region about the direction of the GC. Specialized interstellar emission models (IEMs) are constructed to enable the separation of the.-ray emissions produced by cosmic ray particles interacting with the interstellar gas and radiation fields in the Milky Way into that from the inner similar to 1 kpc surrounding the GC, and that from the rest of the Galaxy. A catalog of point sources for the 15 degrees x 15 degrees region is self-consistently constructed using these IEMs: the First Fermi-LAT Inner Galaxy Point Source Catalog (1FIG). The spatial locations, fluxes, and spectral properties of the 1FIG sources are presented, and compared with gamma-ray point sources over the same region taken from existing catalogs. After subtracting the interstellar emission and point-source contributions a residual is found. If templates that peak toward the GC are used to model the positive residual the agreement with the data improves, but none of the additional templates tried account for all of its spatial structure. The spectrum of the positive residual modeled with these templates has a strong dependence on the choice of IEM.

  • 172. Ajello, M.
    et al.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cutini, S.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Frailis, M.
    Fukazawa, Y.
    Fukui, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashi, K.
    Hays, E.
    Itoh, R.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kubo, H.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S. -H
    Lionetto, A. M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Naumann-Godo, M.
    Nishino, S.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Parent, D.
    Pelassa, V.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Roth, M.
    Sadrozinski, H. F. -W
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Troja, E.
    Uchiyama, Y.
    Uehara, T.
    Usher, T. L.
    Vandenbroucke, J.
    Van Etten, A.
    Vasileiou, V.
    Vianello, G.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yamamoto, H.
    Yamazaki, R.
    Yang, Zhaoyu
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Yasuda, H.
    Ziegler, M.
    Zimmer, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    FERMI LARGE AREA TELESCOPE OBSERVATIONS OF THE SUPERNOVA REMNANT G8.7-0.12012Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 744, nr 1, s. 80-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present a detailed analysis of the GeV gamma-ray emission toward the supernova remnant (SNR) G8.7-0.1 with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. An investigation of the relationship between G8.7-0.1 and the TeV unidentified source HESS J1804-216 provides us with an important clue on diffusion process of cosmic rays if particle acceleration operates in the SNR. The GeV gamma-ray emission is extended with most of the emission in positional coincidence with the SNR G8.7-0.1 and a lesser part located outside the western boundary of G8.7-0.1. The region of the gamma-ray emission overlaps spatially connected molecular clouds, implying a physical connection for the gamma-ray structure. The total gamma-ray spectrum measured with LAT from 200 MeV-100 GeV can be described by a broken power-law function with a break of 2.4 +/- 0.6 (stat) +/- 1.2 (sys) GeV, and photon indices of 2.10 +/- 0.06 (stat) +/- 0.10 (sys) below the break and 2.70 +/- 0.12 (stat) +/- 0.14 (sys) above the break. Given the spatial association among the gamma rays, the radio emission of G8.7-0.1, and the molecular clouds, the decay of pi(0)s produced by particles accelerated in the SNR and hitting the molecular clouds naturally explains the GeV gamma-ray spectrum. We also find that the GeV morphology is not well represented by the TeV emission from HESS J1804-216 and that the spectrum in the GeV band is not consistent with the extrapolation of the TeV gamma-ray spectrum. The spectral index of the TeV emission is consistent with the particle spectral index predicted by a theory that assumes energy-dependent diffusion of particles accelerated in an SNR. We discuss the possibility that the TeV spectrum originates from the interaction of particles accelerated in G8.7-0.1 with molecular clouds, and we constrain the diffusion coefficient of the particles.

  • 173. Ajello, M.
    et al.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Cutini, S.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Enoto, T.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Graham, P.
    Grenier, I. A.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashida, M.
    Hughes, R. E.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lionetto, A. M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Razzano, M.
    Ritz, S.
    Roth, M.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schalk, T. L.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Yang, Z.
    Zimmer, S.
    Limits on large extra dimensions based on observations of neutron stars with the Fermi-LAT2012Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 2, s. 012-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present limits for the compactification scale in the theory of Large Extra Dimensions (LED) proposed by Arkani-Hamed, Dimopoulos, and Dvali. We use 11 months of data from the Fermi Large Area Telescope (Fermi-LAT) to set gamma ray flux limits for 6 gamma-ray faint neutron stars (NS). To set limits on LED we use the model of Hannestad and Raffelt (HR) that calculates the Kaluza-Klein (KK) graviton production in supernova cores and the large fraction subsequently gravitationally bound around the resulting NS. The predicted decay of the bound KK gravitons to gamma gamma should contribute to the flux from NSs. Considering 2 to 7 extra dimensions of the same size in the context of the HR model, we use Monte Carlo techniques to calculate the expected differential flux of gamma-rays arising from these KK gravitons, including the effects of the age of the NS, graviton orbit, and absorption of gamma-rays in the magnetosphere of the NS. We compare our Monte Carlo-based differential flux to the experimental differential flux using maximum likelihood techniques to obtain our limits on LED. Our limits are more restrictive than past EGRET-based optimistic limits that do not include these important corrections. Additionally, our limits are more stringent than LHC based limits for 3 or fewer LED, and comparable for 4 LED. We conclude that if the effective Planck scale is around a TeV, then for 2 or 3 LED the compactification topology must be more complicated than a torus.

  • 174. Ajello, M.
    et al.
    Gasparrini, D.
    Sánchez-Conde, Miguel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stanford University, USA.
    Zaharijas, G.
    Gustafsson, M.
    Cohen-Tanugi, J.
    Dermer, C. D.
    Inoue, Y.
    Hartmann, D.
    Ackermann, M.
    Bechtol, K.
    Franckowiak, A.
    Reimer, A.
    Romani, R. W.
    Strong, A. W.
    THE ORIGIN OF THE EXTRAGALACTIC GAMMA-RAY BACKGROUND AND IMPLICATIONS FOR DARK MATTER ANNIHILATION2015Ingår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 800, nr 2, artikel-id L27Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The origin of the extragalactic.-ray background (EGB) has been debated for some time. The EGB comprises the.-ray emission from resolved and unresolved extragalactic sources, such as blazars, star-forming galaxies, and radio galaxies, as well as radiation from truly diffuse processes. This Letter focuses on the blazar source class, the most numerous detected population, and presents an updated luminosity function and spectral energy distribution model consistent with the blazar observations performed by the Fermi-Large Area Telescope (LAT). We show that blazars account for 50(-11)(+12)% of the EGB photons (>0.1 GeV), and that Fermi-LAT has already resolved similar to 70% of this contribution. Blazars, and in particular hard-spectrum sources such as BL Lacs, are responsible for most of the EGB emission above 100 GeV. We find that the extragalactic background light, which attenuates blazars' high-energy emission, is responsible for the high-energy cutoff observed in the EGB spectrum. Finally, we show that blazars, star-forming galaxies, and radio galaxies can naturally account for the amplitude and spectral shape of the background in the 0.1-820 GeV range, leaving only modest room for other contributions. This allows us to set competitive constraints on the dark matter annihilation cross section.

  • 175. Akiyama, Eiji
    et al.
    Hashimoto, Jun
    Liu, Hauyu Baobabu
    Li, Jennifer I-Hsiu
    Bonnefoy, Michael
    Dong, Ruobing
    Hasegawa, Yasuhiro
    Henning, Thomas
    Sitko, Michael L.
    Janson, Markus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Feldt, Markus
    Wisniewski, John
    Kudo, Tomoyuki
    Kusakabe, Nobuhiko
    Tsukagoshi, Takashi
    Momose, Munetake
    Muto, Takayuki
    Taki, Tetsuo
    Kuzuhara, Masayuki
    Satoshi, Mayama
    Takami, Michihiro
    Ohashi, Nagayoshi
    Grady, Carol A.
    Kwon, Jungmi
    Thalmann, Christian
    Abe, Lyu
    Brandner, Wolfgang
    Brandt, Timothy D.
    Carson, Joseph C.
    Egner, Sebastian
    Goto, Miwa
    Guyon, Olivier
    Hayano, Yutaka
    Hayashi, Masahiko
    Hayashi, Saeko S.
    Hodapp, Klaus W.
    Ishii, Miki
    Iye, Masanori
    Knapp, Gillian R.
    Kandori, Ryo
    Matsuo, Taro
    Mcelwain, Michael W.
    Miyama, Shoken
    Morino, Jun-Ichi
    Moro-Martin, Amaya
    Nishimura, Tetsuo
    Pyo, Tae-Soo
    Serabyn, Eugene
    Suenaga, Takuya
    Suto, Hiroshi
    Suzuki, Ryuji
    Takahashi, Yasuhiro H.
    Takato, Naruhisa
    Terada, Hiroshi
    Tomono, Daigo
    Turner, Edwin L.
    Watanabe, Makoto
    Yamada, Toru
    Takami, Hideki
    Usuda, Tomonori
    Tamura, Motohide
    SPIRAL STRUCTURE AND DIFFERENTIAL DUST SIZE DISTRIBUTION IN THE LkH alpha 330 DISK2016Ingår i: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 152, nr 6, artikel-id 222Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Dust trapping accelerates the coagulation of dust particles, and, thus, it represents an initial step toward the formation of planetesimals. We report H-band (1.6 mu m) linear polarimetric observations and 0.87 mm interferometric continuum observations toward a transitional disk around LkH alpha 330. As a. result, a pair of spiral arms were detected in the H-band emission, and an asymmetric (potentially arm-like) structure was detected in the 0.87 mm continuum emission. We discuss the origin of the spiral arm and the asymmetric structure. and suggest that a massive unseen planet is the most plausible explanation. The possibility of dust trapping and grain growth causing the asymmetric structure was also investigated through the opacity index (beta) by plotting the observed spectral energy distribution slope between 0.87 mm from our Submillimeter Array observation and 1.3 mm from literature. The results imply that grains are indistinguishable from interstellar medium-like dust in the east side (beta = 2.0 +/- 0.5) but are much smaller in the west side beta = 0.7(-0.4)(+0.5), indicating differential dust size distribution between the two sides of the disk. Combining the results of near-infrared and submillimeter observations, we conjecture that the spiral arms exist at the upper surface and an asymmetric structure resides in the disk interior. Future observations at centimeter wavelengths and differential polarization imaging in other bands (Y-K) with extreme AO imagers are required to understand how large dust grains form and to further explore the dust distribution in the disk.

  • 176. Akrami, Y.
    et al.
    Argueso, F.
    Ashdown, M.
    Aumont, J.
    Baccigalupi, C.
    Ballardini, M.
    Banday, A. J.
    Barreiro, R. B.
    Bartolo, N.
    Basak, S.
    Benabed, K.
    Bernard, J-P
    Bersanelli, M.
    Bielewicz, P.
    Bonavera, L.
    Bond, J. R.
    Borrill, J.
    Bouchet, F. R.
    Burigana, C.
    Butler, R. C.
    Calabrese, E.
    Carron, J.
    Chiang, H. C.
    Combet, C.
    Crill, B. P.
    Cuttaia, F.
    de Bernardis, P.
    de Rosa, A.
    de Zotti, G.
    Delabrouille, J.
    Delouis, J-M
    Di Valentino, E.
    Dickinson, C.
    Diego, J. M.
    Ducout, A.
    Dupac, X.
    Efstathiou, G.
    Elsner, F.
    Ensslin, T. A.
    Eriksen, H. K.
    Fantaye, Y.
    Finelli, F.
    Frailis, M.
    Fraisse, A. A.
    Franceschi, E.
    Frolov, A.
    Galeotta, S.
    Galli, S.
    Ganga, K.
    Genova-Santos, R. T.
    Gerbino, Martina
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Ghosh, T.
    Gonzalez-Nuevo, J.
    Gorski, K. M.
    Gratton, S.
    Gruppuso, A.
    Gudmundsson, Jón E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Princeton University, USA.
    Handley, W.
    Hansen, F. K.
    Herranz, D.
    Hivon, E.
    Huang, Z.
    Jaffe, A. H.
    Jones, W. C.
    Keihanen, E.
    Keskitalo, R.
    Kiiveri, K.
    Kim, J.
    Kisner, T. S.
    Krachmalnicoff, N.
    Kunz, M.
    Kurki-Suonio, H.
    Lahteenmaki, A.
    Lamarre, J-M
    Lasenby, A.
    Lattanzi, M.
    Lawrence, C. R.
    Levrier, F.
    Liguori, M.
    Lilje, P. B.
    Lindholm, V
    Lopez-Caniego, M.
    Ma, Y-Z
    Macias-Perez, J. F.
    Maggio, G.
    Maino, D.
    Mandolesi, N.
    Mangilli, A.
    Maris, M.
    Martin, P. G.
    Martinez-Gonzalez, E.
    Matarrese, S.
    McEwen, J. D.
    Meinhold, P. R.
    Melchiorri, A.
    Mennella, A.
    Migliaccio, M.
    Miville-Deschenes, M-A
    Molinari, D.
    Moneti, A.
    Montier, L.
    Morgante, G.
    Natoli, P.
    Oxborrow, C. A.
    Pagano, L.
    Paoletti, D.
    Partridge, B.
    Patanchon, G.
    Pearson, T. J.
    Pettorino, V
    Piacentini, F.
    Polenta, G.
    Puget, J-L
    Rachen, J. P.
    Racine, B.
    Reinecke, M.
    Remazeilles, M.
    Renzi, A.
    Rocha, G.
    Roudier, G.
    Rubino-Martin, J. A.
    Salvati, L.
    Sandri, M.
    Savelainen, M.
    Scott, D.
    Suur-Uski, A-S
    Tauber, J. A.
    Tavagnacco, D.
    Toffolatti, L.
    Tomasi, M.
    Trombetti, T.
    Tucci, M.
    Valiviita, J.
    Van Tent, B.
    Vielva, P.
    Villa, F.
    Vittorio, N.
    Wehus, I. K.
    Zacchei, A.
    Zonca, A.
    Planck intermediate results LIV. The Planck multi-frequency catalogue of non-thermal sources2018Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 619, artikel-id A94Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This paper presents the Planck Multi-frequency Catalogue of Non-thermal (i.e. synchrotron-dominated) Sources (PCNT) observed between 30 and 857 GHz by the ESA Planck mission. This catalogue was constructed by selecting objects detected in the full mission all-sky temperature maps at 30 and 143 GHz, with a signal-to-noise ratio (S/N) > 3 in at least one of the two channels after filtering with a particular Mexican hat wavelet. As a result, 29 400 source candidates were selected. Then, a multi-frequency analysis was performed using the Matrix Filters methodology at the position of these objects, and flux densities and errors were calculated for all of them in the nine Planck channels. This catalogue was built using a different methodology than the one adopted for the Planck Catalogue of Compact Sources (PCCS) and the Second Planck Catalogue of Compact Sources (PCCS2), although the initial detection was done with the same pipeline that was used to produce them. The present catalogue is the first unbiased, full-sky catalogue of synchrotron-dominated sources published at millimetre and submillimetre wavelengths and constitutes a powerful database for statistical studies of non-thermal extragalactic sources, whose emission is dominated by the central active galactic nucleus. Together with the full multi-frequency catalogue, we also define the Bright Planck Multi-frequency Catalogue of Non-thermal Sources (PCNTb), where only those objects with a S/N > 4 at both 30 and 143 GHz were selected. In this catalogue 1146 compact sources are detected outside the adopted Planck GAL070 mask; thus, these sources constitute a highly reliable sample of extragalactic radio sources. We also flag the high-significance subsample (PCNThs), a subset of 151 sources that are detected with S/N > 4 in all nine Planck channels, 75 of which are found outside the Planck mask adopted here. The remaining 76 sources inside the Galactic mask are very likely Galactic objects.

  • 177.
    Akrami, Yashar
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Supersymmetry vis-à-vis Observation: Dark Matter Constraints, Global Fits and Statistical Issues2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Weak-scale supersymmetry is one of the most favoured theories beyond the Standard Model of particle physics that elegantly solves various theoretical and observational problems in both particle physics and cosmology. In this thesis, I describe the theoretical foundations of supersymmetry, issues that it can address and concrete supersymmetric models that are widely used in phenomenological studies. I discuss how the predictions of supersymmetric models may be compared with observational data from both colliders and cosmology. I show why constraints on supersymmetric parameters by direct and indirect searches of particle dark matter are of particular interest in this respect. Gamma-ray observations of astrophysical sources, in particular dwarf spheroidal galaxies, by the Fermi satellite, and recording nuclear recoil events and energies by future ton-scale direct detection experiments are shown to provide powerful tools in searches for supersymmetric dark matter and estimating supersymmetric parameters. I discuss some major statistical issues in supersymmetric global fits to experimental data. In particular, I further demonstrate that existing advanced scanning techniques may fail in correctly mapping the statistical properties of the parameter spaces even for the simplest supersymmetric models. Complementary scanning methods based on Genetic Algorithms are proposed.

  • 178.
    Akrami, Yashar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Savage, Christopher
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Scott, Pat
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Edsjö, Joakim
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    How well will ton-scale dark matter direct detection experiments constrain minimal supersymmetry?2011Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 4, s. 012-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Weakly interacting massive particles (WIMPs) are amongst the most interesting dark matter (DM) candidates. Many DM candidates naturally arise in theories beyond the standard model (SM) of particle physics, like weak-scale supersymmetry (SUSY). Experiments aim to detect WIMPs by scattering, annihilation or direct production, and thereby determine the underlying theory to which they belong, along with its parameters. Here we examine the prospects for further constraining the Constrained Minimal Supersymmetric Standard Model (CMSSM) with future ton-scale direct detection experiments. We consider ton-scale extrapolations of three current experiments: CDMS, XENON and COUPP, with 1000 kg-years of raw exposure each. We assume energy resolutions, energy ranges and efficiencies similar to the current versions of the experiments, and include backgrounds at target levels. Our analysis is based on full likelihood constructions for the experiments. We also take into account present uncertainties on hadronic matrix elements for neutralino-quark couplings, and on halo model parameters. We generate synthetic data based on four benchmark points and scan over the CMSSM parameter space using nested sampling. We construct both Bayesian posterior PDFs and frequentist profile likelihoods for the model parameters, as well as the mass and various cross-sections of the lightest neutralino. Future ton-scale experiments will help substantially in constraining supersymmetry, especially when results of experiments primarily targeting spin-dependent nuclear scattering are combined with those directed more toward spin-independent interactions.

  • 179.
    Akrami, Yashar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Savage, Christopher
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Scott, Pat
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Edsjö, Joakim
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Statistical coverage for supersymmetric parameter estimation: a case study with direct detection of dark matter2011Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 7, s. 002-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Models of weak-scale supersymmetry offer viable dark matter (DM) candidates. Their parameter spaces are however rather large and complex, such that pinning down the actual parameter values from experimental data can depend strongly on the employed statistical framework and scanning algorithm. In frequentist parameter estimation, a central requirement for properly constructed confidence intervals is that they cover true parameter values, preferably at exactly the stated confidence level when experiments are repeated infinitely many times. Since most widely-used scanning techniques are optimised for Bayesian statistics, one needs to assess their abilities in providing correct confidence intervals in terms of the statistical coverage. Here we investigate this for the Constrained Minimal Supersymmetric Standard Model (CMSSM) when only constrained by data from direct searches for dark matter. We construct confidence intervals from one-dimensional profile likelihoods and study the coverage by generating several pseudo-experiments for two benchmark sets of pseudo-true parameters. We use nested sampling to scan the parameter space and evaluate the coverage for the two benchmarks when either flat or logarithmic priors are imposed on gaugino and scalar mass parameters. We observe both under- and over-coverage, which in some cases vary quite dramatically when benchmarks or priors are modified. We show how most of the variation can be explained as the impact of explicit and implicit priors, where the latter are indirectly imposed by physicality conditions. For comparison, we also evaluate the coverage for Bayesian credible intervals, and (predictably) observe significant under-coverage in those cases.

  • 180. Akyuz, A.
    et al.
    Thompson, D. J.
    Donato, D.
    Perkins, J. S.
    Fuhrmann, L.
    Angelakis, E.
    Zensus, J. A.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Sokolovsky, K.
    Kurtanidze, O.
    Long-term multiwavelength studies of high-redshift blazar 0836+7102013Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 556, artikel-id A71Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims. The observation of gamma-ray flares from blazar 0836+710 in 2011, following a period of quiescence, offered an opportunity to study correlated activity at different wavelengths for a high-redshift (z = 2.218) active galactic nucleus.

    Methods. Optical and radio monitoring, plus Fermi-LAT gamma-ray monitoring provided 2008-2012 coverage, while Swift offered auxiliary optical, ultraviolet, and X-ray information. Other contemporaneous observations were used to construct a broad-band spectral energy distribution.

    Results. There is evidence of correlation but not a measurable lag between the optical and.-ray flaring emission. In contrast, there is no clear correlation between radio and gamma-ray activity, indicating radio emission regions that are unrelated to the parts of the jet that produce the gamma rays. The gamma-ray energy spectrum is unusual in showing a change of shape from a power law to a curved spectrum when going from the quiescent state to the active state.

  • 181. Alatalo, K.
    et al.
    Appleton, P. N.
    Lisenfeld, U.
    Bitsakis, T.
    Guillard, P.
    Charmandaris, V.
    Cluver, M.
    Dopita, M. A.
    Freeland, Emily
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Jarrett, T.
    Kewley, L. J.
    Ogle, P. M.
    Rasmussen, J.
    Rich, J. A.
    Verdes-Montenegro, L.
    Xu, C. K.
    Yun, M.
    STRONG FAR-INFRARED COOLING LINES, PECULIAR CO KINEMATICS, AND POSSIBLE STAR-FORMATION SUPPRESSION IN HICKSON COMPACT GROUP 572014Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 795, nr 2, s. 159-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present [C II] and [O I] observations from Herschel and CO(1-0) maps from the Combined Array for Research in Millimeter Astronomy (CARMA) of the Hickson compact group HCG 57, focusing on the galaxies HCG 57a and HCG 57d. HCG 57a has been previously shown to contain enhanced quantities of warm molecular hydrogen consistent with shock or turbulent heating. Our observations show that HCG 57d has strong [C II] emission compared to L-FIR and weak CO(1-0), while in HCG 57a, both the [C II] and CO(1-0) are strong. HCG 57a lies at the upper end of the normal distribution of the [C II]/CO and [C II]/FIR ratios, and its far-infrared (FIR) cooling supports a low-density, warm, diffuse gas that falls close to the boundary of acceptable models of a photon-dominated region. However, the power radiated in the [C II] and warm H-2 emissions have similar magnitudes, as seen in other shock-dominated systems and predicted by recent models. We suggest that shock heating of the [C II] is a viable alternative to photoelectric heating in violently disturbed, diffuse gas. The existence of shocks is also consistent with the peculiar CO kinematics in the galaxy, indicating that highly noncircular motions are present. These kinematically disturbed CO regions also show evidence of suppressed star formation, falling a factor of 10-30 below normal galaxies on the Kennicutt-Schmidt relation. We suggest that the peculiar properties of both galaxies are consistent with a highly dissipative, off-center collisional encounter between HCG 57d and 57a, creating ring-like morphologies in both systems. Highly dissipative gas-on-gas collisions may be more common in dense groups because of the likelihood of repeated multiple encounters. The possibility of shock-induced star-formation suppression may explain why a subset of these HCG galaxies has been found previously to fall in the mid-infrared green valley.

  • 182. Aleksic, J.
    et al.
    Alvarez, E. A.
    Antonelli, L. A.
    Antoranz, P.
    Ansoldi, S.
    Asensio, M.
    Backes, M.
    de Almeida, U. Barres
    Barrio, J. A.
    Bastieri, D.
    Becerra Gonzalez, J.
    Bednarek, W.
    Berger, K.
    Bernardini, E.
    Biland, A.
    Blanch, O.
    Bock, R. K.
    Boller, A.
    Bonnoli, G.
    Tridon, D. Borla
    Bretz, T.
    Canellas, A.
    Carmona, E.
    Carosi, A.
    Colin, P.
    Colombo, E.
    Contreras, J. L.
    Cortina, J.
    Cossio, L.
    Covino, S.
    Da Vela, P.
    Dazzi, F.
    De Angelis, A.
    De Caneva, G.
    De Cea del Pozo, E.
    De Lotto, B.
    Delgado Mendez, C.
    Diago Ortega, A.
    Doert, M.
    Dominguez, A.
    Prester, D. Dominis
    Dorner, D.
    Doro, M.
    Eisenacher, D.
    Elsaesser, D.
    Ferenc, D.
    Fonseca, M. V.
    Font, L.
    Fruck, C.
    Garcia Lopez, R. J.
    Garczarczyk, M.
    Garrido Terrats, D.
    Gaug, M.
    Giavitto, G.
    Godinovic, N.
    Gonzalez Munoz, A.
    Gozzini, S. R.
    Hadasch, D.
    Haefner, D.
    Herrero, A.
    Hildebrand, D.
    Hose, J.
    Hrupec, D.
    Huber, B.
    Jankowski, F.
    Jogler, T.
    Kadenius, V.
    Kellermann, H.
    Klepser, S.
    Krahenbuhl, T.
    Krause, J.
    La Barbera, A.
    Lelas, D.
    Leonardo, E.
    Lewandowska, N.
    Lindfors, E.
    Lombardi, S.
    Lopez, M.
    Lopez-Coto, R.
    Lopez-Oramas, A.
    Lorenz, E.
    Makariev, M.
    Maneva, G.
    Mankuzhiyil, N.
    Mannheim, K.
    Maraschi, L.
    Mariotti, M.
    Martinez, M.
    Mazin, D.
    Meucci, M.
    Miranda, J. M.
    Mirzoyan, R.
    Moldon, J.
    Moralejo, A.
    Munar-Adrover, P.
    Niedzwiecki, A.
    Nieto, D.
    Nilsson, K.
    Nowak, N.
    Orito, R.
    Paiano, S.
    Paneque, D.
    Paoletti, R.
    Pardo, S.
    Paredes, J. M.
    Partini, S.
    Perez-Torres, M. A.
    Persic, M.
    Pilia, M.
    Pochon, J.
    Prada, F.
    Moroni, P. G. Prada
    Prandini, E.
    Puerto Gimenez, I.
    Puljak, I.
    Reichardt, I.
    Reinthal, R.
    Rhode, W.
    Ribo, M.
    Rico, J.
    Ruegamer, S.
    Saggion, A.
    Saito, K.
    Saito, T. Y.
    Salvati, M.
    Satalecka, K.
    Scalzotto, V.
    Scapin, V.
    Schultz, C.
    Schweizer, T.
    Shore, S. N.
    Sillanpaa, A.
    Sitarek, J.
    Snidaric, I.
    Sobczynska, D.
    Spanier, F.
    Spiro, S.
    Stamatescu, V.
    Stamerra, A.
    Steinke, B.
    Storz, J.
    Strah, N.
    Sun, S.
    Suric, T.
    Takalo, L.
    Takami, H.
    Tavecchio, F.
    Temnikov, P.
    Terzic, T.
    Tescaro, D.
    Teshima, M.
    Tibolla, O.
    Torres, D. F.
    Treves, A.
    Uellenbeck, M.
    Vogler, P.
    Wagner, R. M.
    Weitzel, Q.
    Zabalza, V.
    Zandanel, F.
    Zanin, R.
    Berdyugin, A.
    Buson, S.
    Jarvela, E.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Lahteenmaki, A.
    Tammi, J.
    Discovery of VHE gamma-rays from the blazar 1ES 1215+303 with the MAGIC telescopes and simultaneous multi-wavelength observations2012Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 544, s. A142-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context. We present the discovery of very high energy (VHE, E > 100 GeV) gamma-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to gamma-rays. Aims. We study the VHE gamma-ray emission from 1ES 1215+303 and its relation to the emissions in other wavelengths. Methods. Triggered by an optical outburst, MAGIC observed the source in 2011 January-February for 20.3 h. The target was monitored in the optical R-band by the KVA telescope that also performed optical polarization measurements. We triggered target of opportunity observations with the Swift satellite and obtained simultaneous and quasi-simultaneous data from the Fermi Large Area Telescope and from the Metsahovi radio telescope. We also present the analysis of older MAGIC data taken in 2010. Results. The MAGIC observations of 1ES 1215+303 carried out in 2011 January-February resulted in the first detection of the source at VHE with a statistical significance of 9.4 sigma. Simultaneously, the source was observed in a high optical and X-ray state. In 2010 the source was observed in a lower state in optical, X-ray, and VHE, while the GeV gamma-ray flux and the radio flux were comparable in 2010 and 2011. The spectral energy distribution obtained with the 2011 data can be modeled with a simple one zone SSC model, but it requires extreme values for the Doppler factor or the electron energy distribution.

  • 183. Aleksic, J.
    et al.
    Alvarez, E. A.
    Antonelli, L. A.
    Antoranz, P.
    Asensio, M.
    Backes, M.
    Barrio, J. A.
    Bastieri, D.
    Becerra Gonzalez, J.
    Bednarek, W.
    Berdyugin, A.
    Berger, K.
    Bernardini, E.
    Biland, A.
    Blanch, O.
    Bock, R. K.
    Boller, A.
    Bonnoli, G.
    Tridon, D. Borla
    Braun, I.
    Bretz, T.
    Canellas, A.
    Carmona, E.
    Carosi, A.
    Colin, P.
    Colombo, E.
    Contreras, J. L.
    Cortina, J.
    Cossio, L.
    Covino, S.
    Dazzi, F.
    De Angelis, A.
    De Caneva, G.
    De Cea del Pozo, E.
    De Lotto, B.
    Delgado Mendez, C.
    Diago Ortega, A.
    Doert, M.
    Dominguez, A.
    Prester, D. Dominis
    Dorner, D.
    Doro, M.
    Elsaesser, D.
    Ferenc, D.
    Fonseca, M. V.
    Font, L.
    Fruck, C.
    Garcia Lopez, R. J.
    Garczarczyk, M.
    Garrido, D.
    Giavitto, G.
    Godinovic, N.
    Hadasch, D.
    Haefner, D.
    Herrero, A.
    Hildebrand, D.
    Ohne-Moench, D. H.
    Hose, J.
    Hrupec, D.
    Huber, B.
    Jogler, T.
    Kellermann, H.
    Klepser, S.
    Kraehenbuehl, T.
    Krause, J.
    La Barbera, A.
    Lelas, D.
    Leonardo, E.
    Lindfors, E.
    Lombardi, S.
    Lopez, M.
    Lopez-Oramas, A.
    Lorenz, E.
    Makariev, M.
    Maneva, G.
    Mankuzhiyil, N.
    Mannheim, K.
    Maraschi, L.
    Mariotti, M.
    Martinez, M.
    Mazin, D.
    Meucci, M.
    Miranda, J. M.
    Mirzoyan, R.
    Miyamoto, H.
    Moldon, J.
    Moralejo, A.
    Munar-Adrover, P.
    Nieto, D.
    Nilsson, K.
    Orito, R.
    Oya, I.
    Paneque, D.
    Paoletti, R.
    Pardo, S.
    Paredes, J. M.
    Partini, S.
    Pasanen, M.
    Pauss, F.
    Perez-Torres, M. A.
    Persic, M.
    Peruzzo, L.
    Pilia, M.
    Pochon, J.
    Prada, F.
    Moroni, P. G. Prada
    Prandini, E.
    Puljak, I.
    Reichardt, I.
    Reinthal, R.
    Rhode, W.
    Ribo, M.
    Rico, J.
    Ruegamer, S.
    Saggion, A.
    Saito, K.
    Saito, T. Y.
    Salvati, M.
    Satalecka, K.
    Scalzotto, V.
    Scapin, V.
    Schultz, C.
    Schweizer, T.
    Shayduk, M.
    Shore, S. N.
    Sillanpaa, A.
    Sitarek, J.
    Sobczynska, D.
    Spanier, F.
    Spiro, S.
    Stamatescu, V.
    Stamerra, A.
    Steinke, B.
    Storz, J.
    Strah, N.
    Suric, T.
    Takalo, L.
    Takami, H.
    Tavecchio, F.
    Temnikov, P.
    Terzic, T.
    Tescaro, D.
    Teshima, M.
    Tibolla, O.
    Torres, D. F.
    Treves, A.
    Uellenbeck, M.
    Vankov, H.
    Vogler, P.
    Wagner, R. M.
    Weitzel, Q.
    Zabalza, V.
    Zandanel, F.
    Zanin, R.
    Buson, S.
    Horan, D.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    D'Ammando, F.
    PG 1553+113: FIVE YEARS OF OBSERVATIONS WITH MAGIC2012Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 748, nr 1, s. 46-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We present the results of five years (2005-2009) of MAGIC observations of the BL Lac object PG 1553+113 at very high energies (VHEs; E > 100 GeV). Power-law fits of the individual years are compatible with a steady mean photon index Gamma = 4.27 +/- 0.14. In the last three years of data, the flux level above 150 GeV shows a clear variability (probability of constant flux < 0.001%). The flux variations are modest, lying in the range from 4% to 11% of the Crab Nebula flux. Simultaneous optical data also show only modest variability that seems to be correlated with VHE gamma-ray variability. We also performed a temporal analysis of (all available) simultaneous Fermi/Large Area Telescope data of PG 1553+113 above 1 GeV, which reveals hints of variability in the 2008-2009 sample. Finally, we present a combination of the mean spectrum measured at VHEs with archival data available for other wavelengths. The mean spectral energy distribution can be modeled with a one-zone synchrotron self-Compton model, which gives the main physical parameters governing the VHE emission in the blazar jet.

  • 184. Aleksic, J.
    et al.
    Ansoldi, S.
    Antonelli, L. A.
    Antoranz, P.
    Babic, A.
    Bangale, P.
    de Almeida, U. Barres
    Barrio, J. A.
    Becerra Gonzalez, J.
    Bednarek, W.
    Bernardini, E.
    Biland, A.
    Blanch, O.
    Bonnefoy, S.
    Bonnoli, G.
    Borracci, F.
    Bretz, T.
    Carmona, E.
    Carosi, A.
    Carreto Fidalgo, D.
    Colin, P.
    Colombo, E.
    Contreras, J. L.
    Cortina, J.
    Covino, S.
    Da Vela, P.
    Dazzi, F.
    De Angelis, A.
    De Caneva, G.
    De Lotto, B.
    Delgado Mendez, C.
    Doert, M.
    Dominguez, A.
    Prester, D. Dominis
    Dorner, D.
    Doro, M.
    Einecke, S.
    Eisenacher, D.
    Elsaesser, D.
    Farina, E.
    Ferenc, D.
    Fonseca, M. V.
    Font, L.
    Frantzen, K.
    Fruck, C.
    Garcia Lopez, R. J.
    Garczarczyk, M.
    Garrido Terrats, D.
    Gaug, M.
    Godinovic, N.
    Gonzalez Munoz, A.
    Gozzini, S. R.
    Hadasch, D.
    Hayashida, M.
    Herrera, J.
    Herrero, A.
    Hildebrand, D.
    Hose, J.
    Hrupec, D.
    Idec, W.
    Kadenius, V.
    Kellermann, H.
    Klepser, S.
    Kodani, K.
    Konno, Y.
    Krause, J.
    Kubo, H.
    Kushida, J.
    La Barbera, A.
    Lelas, D.
    Lewandowska, N.
    Lindfors, E.
    Lombardi, S.
    Lopez, M.
    Lopez-Coto, R.
    Lopez-Oramas, A.
    Lorenz, E.
    Lozano, I.
    Makariev, M.
    Mallot, K.
    Maneva, G.
    Mankuzhiyil, N.
    Mannheim, K.
    Maraschi, L.
    Marcote, B.
    Mariotti, M.
    Martinez, M.
    Mazin, D.
    Menzel, U.
    Meucci, M.
    Miranda, J. M.
    Mirzoyan, R.
    Moralejo, A.
    Munar-Adrover, P.
    Nakajima, D.
    Niedzwiecki, A.
    Nilsson, K.
    Nishijima, K.
    Noda, K.
    Nowak, N.
    de Ona Wilhelmi, E.
    Orito, R.
    Overkemping, A.
    Paiano, S.
    Palatiello, M.
    Paneque, D.
    Paoletti, R.
    Paredes, J. M.
    Paredes-Fortuny, X.
    Partini, S.
    Persic, M.
    Prada, F.
    Moroni, P. G. Prada
    Prandini, E.
    Preziuso, S.
    Puljak, I.
    Reinthal, R.
    Rhode, W.
    Ribo, M.
    Rico, J.
    Garcia, J. Rodriguez
    Ruegamer, S.
    Saggion, A.
    Saito, T.
    Saito, K.
    Satalecka, K.
    Scalzotto, V.
    Scapin, V.
    Schultz, C.
    Schweizer, T.
    Shore, S. N.
    Sillanpaa, A.
    Sitarek, J.
    Snidaric, I.
    Sobczynska, D.
    Spanier, F.
    Stamatescu, V.
    Stamerra, A.
    Steinbring, T.
    Storz, J.
    Strzys, M.
    Sun, S.
    Suric, T.
    Takalo, L.
    Takami, H.
    Tavecchio, F.
    Temnikov, P.
    Terzic, T.
    Tescaro, D.
    Teshima, M.
    Thaele, J.
    Tibolla, O.
    Torres, D. F.
    Toyama, T.
    Treves, A.
    Uellenbeck, M.
    Vogler, P.
    Wagner, Robert M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Max-Planck-Institut für Physik, Germany.
    Zandanel, F.
    Zanin, R.
    MAGIC reveals a complex morphology within the unidentified gamma-ray source HESS J1857+0262014Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 571, artikel-id A96Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims. HESS J1857+026 is an extended TeV gamma-ray source that was discovered by H. E. S. S. as part of its Galactic plane survey. Given its broadband spectral energy distribution and its spatial coincidence with the young energetic pulsar PSR J1856+0245, the source has been put forward as a pulsar wind nebula (PWN) candidate. MAGIC has performed follow-up observations aimed at mapping the source down to energies approaching 100 GeV in order to better understand its complex morphology. Methods. HESS J1857+026 was observed by MAGIC in 2010, yielding 29 h of good quality stereoscopic data that allowed us to map the source region in two separate ranges of energy. Results. We detected very-high-energy gamma-ray emission from HESS J1857+026 with a significance of 12 sigma above 150 GeV. The differential energy spectrum between 100 GeV and 13 TeV is described well by a power law function dN/dE = N-0(E/1TeV)(-Gamma) with N-0 = (5.37 +/- 0.44(stat) +/- 1.5(sys)) X 10(-12) (TeV-1 cm(-2) s(-1)) and Gamma = 2.16 +/- 0.07(stat) +/- 0.15(sys), which bridges the gap between the GeV emission measured by Fermi-LAT and the multi-TeV emission measured by H.E.S.S.. In addition, we present a detailed analysis of the energy-dependent morphology of this region. We couple these results with archival multiwavelength data and outline evidence in favor of a two-source scenario, whereby one source is associated with a PWN, while the other could be linked with a molecular cloud complex containing an HII region and a possible gas cavity.

  • 185. Alexoudi, X.
    et al.
    Mallonn, M.
    von Essen, C.
    Turner, J. D.
    Keles, E.
    Southworth, J.
    Mancini, L.
    Ciceri, Simona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Granzer, T.
    Denker, C.
    Dineva, E.
    Strassmeier, K. G.
    Deciphering the atmosphere of HAT-P-12b: solving discrepant results2018Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 620, artikel-id A142Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Context. Two independent investigations of the atmosphere of the hot Jupiter HAT-P-12b by two different groups resulted in discrepant solutions. Using broad-band photometry from the ground, one study found a flat and featureless transmission spectrum that was interpreted as gray absorption by dense cloud coverage. The second study made use of Hubble Space Telescope (HST) observations and found Rayleigh scattering at optical wavelengths caused by haze. Aims. The main purpose of this work is to determine the source of this inconsistency and provide feedback to prevent similar discrepancies in future analyses of other exoplanetary atmospheres. Methods. We studied the observed discrepancy via two methods. With further broad-band observations in the optical wavelength regions, we strengthened the previous measurements in precision, and with a homogeneous reanalysis of the published data, we were able to assess the systematic errors and the independent analyses of the two different groups. Results. Repeating the analysis steps of both works, we found that deviating values for the orbital parameters are the reason for the aforementioned discrepancy. Our work showed a degeneracy of the planetary spectral slope with these parameters. In a homogeneous reanalysis of all data, the two literature data sets and the new observations converge to a consistent transmission spectrum, showing a low-amplitude spectral slope and a tentative detection of potassium absorption.

  • 186. Alho, T.
    et al.
    Puletti, V. Giangreco M.
    Pourhasan, R.
    Thorlacius, Lárus
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). University of Iceland, Iceland.
    Monopole correlation functions and holographic phases of matter in 2+1 dimensions2016Ingår i: Physical Review D, ISSN 2470-0010, Vol. 94, nr 10, artikel-id 106012Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The strong coupling dynamics of a 2 + 1 dimensional U(1) gauge theory coupled to charged matter is holographically modeled via a top-down construction with intersecting D3-and D5-branes. We explore the resulting phase diagram at finite temperature and charge density using correlation functions of monopole operators, dual to magnetically charged particles in the higher-dimensional bulk theory, as a diagnostic.

  • 187.
    Ali, Safdar
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Orban, Istvan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Mahmood, S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Loch, S. D.
    Schuch, Reinhold
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Experimental rate coefficients of F5+ recombining into F4+2013Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 557, s. Article nr.-A2Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recombination spectra of F5+ producing F4+ have been investigated with high-energy resolution, using the CRYRING heavy-ion storage ring. The absolute recombination rate coefficients are derived in the centre-of-mass energy range of 0-25 eV. The experimental results are compared with intermediate-coupling AUTOSTRUCTURE calculations for 2s-2p (Delta n = 0) core excitation and show very good agreement in the resonance energy positions and intensities. Trielectronic recombination with 2s(2)-2p(2) transitions are clearly identified in the spectrum. Contributions from F5+ ions in an initial metastable state are also considered. The energy-dependent recombination spectra are convoluted with Maxwell-Boltzmann energy distribution in the 10(3)-10(6) K temperature range. The resulting temperature-dependent rate coefficients are compared with theoretical results from the literature. In the 10(3)-10(4) K range, the calculated data significantly underestimates the plasma recombination rate coefficients. Above 8 x 10(4) K, our AUTOSTRUCTURE results and plasma rate coefficients from elsewhere show agreement that is better than 25% with the experimental results.

  • 188. Allafort, A.
    et al.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Bellazzini, R.
    Bonamente, E.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Chaves, R. C. G.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    D'Ammando, F.
    de Palma, F.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Favuzzi, C.
    Ferrara, E. C.
    Franckowiak, A.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hayashida, M.
    Hayashi, K.
    Hays, E.
    Hewitt, J.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Jogler, T.
    Johnson, A. S.
    Johnson, T. J.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lubrano, P.
    Malyshev, D.
    Marelli, M.
    Mayer, M.
    Mazziotta, M. N.
    Mehault, J.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Paneque, D.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Ray, P. S.
    Razzano, M.
    Reimer, O.
    Reposeur, T.
    Romani, R. W.
    Sartori, A.
    Parkinson, P. M. Saz
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Spinelli, P.
    Strong, A. W.
    Takahashi, H.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Venter, C.
    Vianello, G.
    Vitale, V.
    Winer, B. L.
    Wood, K. S.
    PSR J2021+4026 IN THE GAMMA CYGNI REGION: THE FIRST VARIABLE gamma-RAY PULSAR SEEN BY THE Fermi LAT2013Ingår i: ASTROPHYS J LETT, ISSN 2041-8205, Vol. 777, nr 1, s. L2-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Long-term monitoring of PSR J2021+4026 in the heart of the Cygnus region with the Fermi Large Area Telescope unveiled a sudden decrease in flux above 100 MeV over a timescale shorter than a week. The jump was near MJD 55850 (2011 October 16), with the flux decreasing from (8.33+/-0.08) x 10(-10) erg cm(-2) s(-1) to (6.86+/-0.13) x 10(-10) erg cm(-2) s(-1). Simultaneously, the frequency spindown rate increased from (7.8 +/- 0.1) x 10(-13) Hz s(-1) to (8.1 +/- 0.1) x 10(-13) Hz s(-1). Significant (>5 sigma) changes in the pulse profile and marginal (<3 sigma) changes in the emission spectrum occurred at the same time. There is also evidence for a small, steady flux increase over the 3 yr preceding MJD 55850. This is the first observation at gamma-ray energies of mode changes and intermittent behavior, observed at radio wavelengths for other pulsars. We argue that the change in pulsed gamma-ray emission is due to a change in emission beaming and we speculate that it is precipitated by a shift in the magnetic field structure, leading to a change of either effective magnetic inclination or effective current.

  • 189. Alp, Dennis
    et al.
    Larsson, Josefin
    Maeda, Keiichi
    Fransson, Claes
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Wongwathanarat, Annop
    Gabler, Michael
    Janka, Hans-Thomas
    Jerkstrand, Anders
    Heger, Alexander
    Menon, Athira
    X-Ray and Gamma-Ray Emission from Core-collapse Supernovae: Comparison of Three-dimensional Neutrino-driven Explosions with SN 1987A2019Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 882, nr 1, artikel-id 22Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    During the first few hundred days after the explosion, core-collapse supernovae (SNe) emit down-scattered X-rays and gamma-rays originating from radioactive line emissions, primarily from the Ni-56 -> Co-56 -> Fe-56 chain. We use supernova (SN) models based on three-dimensional neutrino-driven explosion simulations of single stars and mergers to compute this emission and compare the predictions with observations of SN 1987A. A number of models are clearly excluded, showing that high-energy emission is a powerful way of discriminating between models. The best models are almost consistent with the observations, but differences that cannot be matched by a suitable choice of viewing angle are evident. Therefore, our self-consistent models suggest that neutrino-driven explosions are able to produce, in principle, sufficient mixing, although remaining discrepancies may require small changes to the progenitor structures. The soft X-ray cutoff is primarily determined by the metallicity of the progenitor envelope. The main effect of asymmetries is to vary the flux level by a factor of similar to 3. For the more asymmetric models, the shapes of the light curves also change. In addition to the models of SN 1987A, we investigate two models of SNe II-P and one model of a stripped-envelope SN IIb. The Type II-P models have observables similar to those of the models of SN 1987A, but the stripped-envelope SN model is significantly more luminous and evolves faster. Finally, we make simple predictions for future observations of nearby SNe.

  • 190. Alsubai, Khalid
    et al.
    Mislis, Dimitris
    Tsvetanov, Zlatan I.
    Latham, David W.
    Bieryla, Allyson
    Buchhave, Lars A.
    Esquerdo, Gilbert A.
    Bramich, D. M.
    Pyrzas, Stylianos
    Vilchez, Nicolas P. E.
    Mancini, Luigi
    Southworth, John
    Evans, Daniel F.
    Henning, Thomas
    Ciceri, Simona
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi. Max Planck Institute for Astronomy, Germany.
    Qatar Exoplanet Survey: Qatar-3b, Qatar-4b, and Qatar-5b2017Ingår i: Astronomical Journal, ISSN 0004-6256, E-ISSN 1538-3881, Vol. 153, nr 4, artikel-id 200Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report the discovery of Qatar-3b, Qatar-4b, and Qatar-5b, three new transiting planets identified by the Qatar Exoplanet Survey. The three planets belong to the hot Jupiter family, with orbital periods of P-Q3b = 2.50792 days, P-Q4b = 1.80539 days, and P-Q5b = 2.87923 days. Follow-up spectroscopic observations reveal the masses of the planets to be M-Q3b = 4.31 +/- 0.47 M-J, M-Q4b = 6.10 +/- 0.54 M-J, and M-Q5b = 4.32 +/- 0.18 M-J, while model fits to the transit light curves yield radii of R-Q3b = 1.096 +/- 0.14 RJ, R-Q4b = 1.135 +/- 0.11 R-J, and R-Q5b = 1.107 +/- 0.064 R-J. The host stars are low-mass main sequence stars with masses and radii M-Q3 = 1.145 +/- 0.064 M circle dot, M-Q4 = 0.896 +/- 0.048 M circle dot, M-Q5 = 1.128 +/- 0.056 M circle dot and R-Q3 = 1.272 +/- 0.14 R circle dot, R-Q4 = 0.849 +/- 0.063 R circle dot, and R-Q5 = 1.076 +/- 0.051 R circle dot for Qatar-3, 4, and 5 respectively. The V magnitudes of the three host stars are V-Q3 = 12.88, V-Q4 = 13.60, and V-Q5 = 12.82. All three new planets can be classified as heavy hot Jupiters (M > 4 M-J).

  • 191. Altavilla, G.
    et al.
    Stehle, M.
    Ruiz-Lapuente, P.
    Mazzali, P.
    Pignata, G.
    Balastegui, A.
    Benetti, S.
    Blanc, G.
    Canal, R.
    Elias-Rosa, N.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Harutyunyan, A.
    Pastorello, A.
    Patat, F.
    Rich, J.
    Salvo, M.
    Schmidt, B. P.
    Stanishev, V.
    Taubenberger, S.
    Hillebrandt, W.
    The early spectral evolution of SN2004dt2007Ingår i: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 475, nr 2, s. 585-595Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aims. We study the optical spectroscopic properties of Type Ia Supernova (SNIa) 2004dt, focusing our attention on the early epochs. Methods. Observation triggered soon after the SN 2004dt discovery allowed us to obtain a spectrophotometric coverage from day -10 to almost one year (similar to 353 days) after the B band maximum. Observations carried out on an almost daily basis allowed us a good sampling of the fast spectroscopic evolution of SN 2004dt in the early stages. To obtain this result, low-resolution, long-slit spectroscopy was obtained using a number of facilities. Results. This supernova, which in some absorption lines of its early spectra showed the highest degree of polarization ever measured in any SN Ia, has a complex velocity structure in the outer layers of its ejecta. Unburnt oxygen is present, moving at velocities as high as similar to 16 700 km s(-1), with some intermediate-mass elements (Mg, Si, Ca) moving equally fast. Modeling of the spectra based on standard density profiles of the ejecta fails to reproduce the observed features, whereas enhancing the density of outer layers significantly improves the fit. Our analysis indicates the presence of clumps of high-velocity, intermediate-mass elements in the outermost layers, which is also suggested by the spectropolarimetric data.

  • 192.
    Amanullah, R.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Clement, B.
    Cuby, J. -G
    Dahle, H.
    Dahlen, T.
    Hjorth, J.
    Fabbro, S.
    Jönsson, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Kneib, J. -P
    Lidman, C.
    Limousin, M.
    Milvang-Jensen, B.
    Mortsell, E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Nordin, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Paech, K.
    Richard, J.
    Riehm, Teresa
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Stanishev, V.
    Watson, D.
    A HIGHLY MAGNIFIED SUPERNOVA AT z=1.703 BEHIND THE MASSIVE GALAXY CLUSTER A16892011Ingår i: ASTROPHYS J LETT, ISSN 2041-8205, Vol. 742, nr 1, s. L7-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Our ability to study the most remote supernova explosions, crucial for the understanding of the evolution of the high-redshift universe and its expansion rate, is limited by the light collection capabilities of telescopes. However, nature offers unique opportunities to look beyond the range within reach of our unaided instruments thanks to the light-focusing power of massive galaxy clusters. Here we report on the discovery of one of the most distant supernovae ever found, at redshift z = 1.703. Due to a lensing magnification factor of 4.3 +/- 0.3, we are able to measure a light curve of the supernova, as well as spectroscopic features of the host galaxy with a precision comparable to what would otherwise only be possible with future generation telescopes.

  • 193.
    Amanullah, Rahman
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Observations of distant supernovae and cosmological implications2006Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Type Ia supernovae can be used as distance indicators for probing the expansion history of the Universe. The method has proved to be an efficient tool in cosmology and played a decisive role in the discovery of a yet unknown energy form, dark energy, that drives the accelerated expansion of the Universe. The work in this thesis addresses the nature of dark energy, both by presenting existing data, and by predicting opportunities and difficulties related to possible future data.

    Optical and infrared measurements of type Ia supernovae for different epochs in the cosmic expansion history are presented along with a discussion of the systematic errors. The data have been obtained with several instruments, and an optimal method for measuring the lightcurve of a background contaminated source has been used. The procedure was also tested by applying it on simulated images.

    The future of supernova cosmology, and the target precision of cosmological parameters for the proposed SNAP satellite are discussed. In particular, the limits that can be set on various dark energy scenarios are investigated. The possibility of distinguishing between different inverse power-law quintessence models is also studied. The predictions are based on calculations made with the Supernova Observation Calculator, a software package, introduced in the thesis, for simulating the light propagation from distant objects. This tool has also been used for investigating how SNAP observations could be biased by gravitational lensing, and to what extent this would affect cosmology fitting. An alternative approach for estimating cosmological parameters, where lensing effects are taken into account, is also suggested. Finally, it is investigated to what extent strongly lensed core-collapse supernovae could be used as an alternative approach for determining cosmological parameters.

  • 194.
    Amanullah, Rahman
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Johansson, Joel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Banerjee, D. P. K.
    Venkataraman, V.
    Joshi, V.
    Ashok, N. M.
    Cao, Y.
    Kasliwal, M. M.
    Kulkarni, S. R.
    Nugent, P. E.
    Petrushevska, Tanja
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Stanishev, V.
    THE PECULIAR EXTINCTION LAW OF SN 2014J MEASURED WITH THE HUBBLE SPACE TELESCOPE2014Ingår i: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 788, nr 2, s. L21-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The wavelength dependence of the extinction of Type Ia SN 2014J in the nearby galaxy M82 has been measured using UV to near-IR photometry obtained with the Hubble Space Telescope, the Nordic Optical Telescope, and the Mount Abu Infrared Telescope. This is the first time that the reddening of an SN Ia is characterized over the full wavelength range of 0.2-2 mu m. A total-to-selective extinction, R-V >= 3.1, is ruled out with high significance. The best fit at maximum using a Galactic type extinction law yields R-V = 1.4 +/- 0.1. The observed reddening of SN 2014J is also compatible with a power-law extinction, A(lambda)/A(V) = (lambda/lambda(V))(p) as expected from multiple scattering of light, with p = -2.1 +/- 0.1. After correcting for differences in reddening, SN 2014J appears to be very similar to SN 2011 fe over the 14 broadband filter light curves used in our study.

  • 195. Amarsi, A. M.
    et al.
    Asplund, M.
    Collet, R.
    Leenaarts, Jorrit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Non-LTE oxygen line formation in 3D hydrodynamic model stellar atmospheres2016Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 455, nr 4, s. 3735-3751Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The O (Iota) 777 nm lines are among the most commonly used diagnostics for the oxygen abundances in the atmospheres of FGK-type stars. However, they form in conditions that are far from local thermodynamic equilibrium (LTE). We explore the departures from LTE of atomic oxygen, and their impact on O I lines, across the STAGGER-grid of three-dimensional hydrodynamic model atmospheres. For the O (Iota) 777 nm triplet, we find significant departures from LTE. These departures are larger in stars with larger effective temperatures, smaller surface gravities, and larger oxygen abundances. We present grids of predicted 3D non-LTE based equivalent widths for the O (Iota) 616 nm, [O (Iota)] 630 nm, [O (I)] 636 nm, and O (Iota) 777 nm lines, as well as abundance corrections to 1D LTE based results.

  • 196. Amarsi, A. M.
    et al.
    Asplund, M.
    Collet, R.
    Leenaarts, Jorrit
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    The Galactic chemical evolution of oxygen inferred from 3D non-LTE spectral-line-formation calculations2015Ingår i: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 454, nr 1, s. L11-L15Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We revisit the Galactic chemical evolution of oxygen, addressing the systematic errors inherent in classical determinations of the oxygen abundance that arise from the use of one-dimensional (1D) hydrostatic model atmospheres and from the assumption of local thermodynamic equilibrium (LTE). We perform detailed 3D non-LTE radiative-transfer calculations for atomic oxygen lines across a grid of 3D hydrodynamic STAGGER model atmospheres for dwarfs and subgiants. We apply our grid of predicted line strengths of the [O I] 630 nm and O I 777 nm lines using accurate stellar parameters from the literature. We infer a steep decay in [O/Fe] for [Fe/H] greater than or similar to -1.0, a plateau [O/Fe] approximate to 0.5 down to [Fe/H] approximate to -2.5, and an increasing trend for [Fe/H] less than or similar to -2.5. Our 3D non-LTE calculations yield overall concordant results from the two oxygen abundance diagnostics.

  • 197.
    Anderson, Brandon
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Zimmer, Stephan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Conrad, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC). Wallenberg Academy Fellow, Sweden.
    Gustafsson, M.
    Sánchez-Conde, Miguel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum. Stockholms universitet, Naturvetenskapliga fakulteten, Oskar Klein-centrum för kosmopartikelfysik (OKC).
    Caputo, R.
    Search for Gamma-ray Lines Towards Galaxy Clusters with the Fermi-LAT2016Ingår i: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, nr 2, artikel-id 026Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report on a search for monochromatic gamma-ray features in the spectra of galaxy clusters observed by the Fermi Large Area Telescope. Galaxy clusters are the largest structures in the Universe that are bound by dark matter (DM), making them an important testing ground for possible self-interactions or decays of the DM particles. Monochromatic gamma-ray lines provide a unique signature due to the absence of astrophysical backgrounds and are as such considered a smoking-gun signature for new physics. An unbinned joint likelihood analysis of the sixteen most promising clusters using five years of data at energies between 10 and 400 GeV revealed no significant features. For the case of self-annihilation, we set upper limits on the monochromatic velocity-averaged interaction cross section. These limits are compatible with those obtained from observations of the Galactic Center, albeit weaker due to the larger distance to the studied clusters.

  • 198.
    Andersson, K.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Peterson, J. R.
    Madejski, G.
    Application of an XMM-Newton epic Monte Carlo technique to analysis and interpretation of data for the abell 1689, RX J0658-55, and centaurus clusters of galaxies2007Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 670, nr 2, s. 1010-1026Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We propose a new Monte Carlo method to study extended X-ray sources with the European Photon Imaging Camera (EPIC) aboard XMM-Newton. The smoothed particle inference (SPI) technique, described in a companion paper, is applied here to the EPIC data for the clusters of galaxies Abell 1689, Centaurus, and RX J0658-55 (the ""bullet cluster""). We aim to show the advantages of this method of simultaneous spectral and spatial modeling over traditional X-ray spectral analysis. In Abell 1689 we confirm our earlier findings about structure in the temperature distribution and produce a high-resolution temperature map. We also find a hint of velocity structure within the gas, consistent with previous findings. In the bullet cluster, RX J0658-55, we produce the highest resolution temperature map ever to be published of this cluster, allowing us to trace what looks like the trail of the motion of the bullet in the cluster. We even detect a south-to-north temperature gradient within the bullet itself. In the Centaurus cluster we detect, by dividing up the luminosity of the cluster in bands of gas temperatures, a striking feature to the northeast of the cluster core. We hypothesize that this feature is caused by a subcluster left over from a substantial merger that slightly displaced the core. We conclude that our method is very powerful in determining the spatial distributions of plasma temperatures and very useful for systematic studies in cluster structure.

  • 199.
    Andersson, Karl
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Peterson, J. R.
    Madejski, G.
    Goobar, Ariel
    Stockholms universitet, Naturvetenskapliga fakulteten, Fysikum.
    Characterizing the Properties of Clusters of Galaxies as a Function of Luminosity and Redshift2009Ingår i: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 696, s. 1029-1050Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We report the application of the new Monte Carlo method, smoothed particle inference (SPI, described in a pair of companion papers), toward analysis and interpretation of X-ray observations of clusters of galaxies with the XMM-Newton satellite. Our sample consists of publicly available well exposed observations of clusters at redshifts z > 0.069, totaling 101 objects. We determine the luminosity and temperature structure of the X-ray emitting gas, with the goal to quantify the scatter and the evolution of the LX -T relation, as well as to investigate the dependence on cluster substructure with redshift. This work is important for the establishment of the potential robustness of mass estimates from X-ray data which in turn is essential toward the use of clusters for measurements of cosmological parameters. We use the luminosity and temperature maps derived via the SPI technique to determine the presence of cooling cores, via measurements of luminosity and temperature contrast. The LX -T relation is investigated, and we confirm that LX vprop T 3. We find a weak redshift dependence (\propto (1+z)^{\beta _{LT}}, \beta _{LT}=0.50 \pm 0.34), in contrast to some Chandra results. The level of dynamical activity is established using the "power ratio" method, and we compare our results to previous application of this method to Chandra data for clusters. We find signs of evolution in the P 3/P 0 power ratio. A new method, the "temperature two-point correlation function," is proposed. This method is used to determine the "power spectrum" of temperature fluctuations in the X-ray emitting gas as a function of spatial scale. We show how this method can be fruitfully used to identify cooling core clusters as well as those with disturbed structures, presumably due to ongoing or recent merger activity.

  • 200.
    Andersson Lundgren, Andreas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för astronomi.
    Molecular gas in the galaxy M83: Its distribution, kinematics, and relation to star formation2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The barred spiral galaxy M83 (NGC5236) has been observed in the 12CO J=1–0 and J=2–1 millimetre lines with the Swedish-ESO Submillimetre Telescope (SEST). The sizes of the CO maps are 100×100, and they cover the entire optical disk. The CO emission is strongly peaked toward the nucleus. The molecular spiral arms are clearly resolved and can be traced for about 360º. The total molecular gas mass is comparable to the total Hi mass, but H2 dominates in the optical disk.

    Iso-velocity maps show the signature of an inclined, rotating disk, but also the effects of streaming motions along the spiral arms. The dynamical mass is determined and compared to the gas mass. The pattern speed is determined from the residual velocity pattern, and the locations of various resonances are discussed. The molecular gas velocity dispersion is determined, and a trend of decreasing dispersion with increasing galactocentric radius is found.

    A total gas (H2+Hi+He) mass surface density map is presented, and compared to the critical density for star formation of an isothermal gaseous disk. The star formation rate (SFR) in the disk is estimated using data from various star formation tracers. The different SFR estimates agree well when corrections for extinctions, based on the total gas mass map, are made. The radial SFR distribution shows features that can be associated with kinematic resonances. We also find an increased star formation efficiency in the spiral arms. Different Schmidt laws are fitted to the data. The star formation properties of the nuclear region, based on high angular resolution HST data, are also discussed.

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