Change search
Refine search result
30313233343536 1601 - 1650 of 109072
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1601.
    Ahangaran, Reyhaneh
    Stockholm University, Faculty of Social Sciences, Department of Psychology.
    Psykologer inom BUP - hur talar de om sexualitet med ungdomar?2008Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Sexualitet är en viktig del av varje människas liv. För ungdomar utgör sexualiteten en tydlig del i vuxenblivandet och i skapandet av en identitet. Då sexologi saknas som ämne på psykologutbildningen och utifrån mitt intresse för ungdomar aktualiserades frågeställningen för denna undersökning - hur talar psykologer som jobbar inom BUP om sexualitet med ungdomar i terapi? En kvalitativ intervjustudie med nio psykologer genomfördes och analyserades enligt tematisk metod. Svaren visade att de flesta intervjuade psykologerna känner en osäkerhet kring att prata om sexualitet. Detta beror främst på att de har en bristande utbildning och kunskap om ämnet. Visserligen finns goda undantag från detta men de psykologerna är just undantag. Detta väcker tankar om att sexologi måste införas på psykologutbildningen för att kunna garantera såväl ungdomar som vuxna patienter en god psykiatrisk vård där alla aspekter av livet bemöts på ett professionellt och respektfullt sätt.

  • 1602.
    Aharbach, Fouzia
    et al.
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Ehn, Jenny
    Stockholm University, Faculty of Social Sciences, Department of Education.
    Ser mitt huvud smart ut i den här?: en studie om sjalbärande kvinnors upplevelser av bemötande inom högskolan2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This study aims to describe the experiences of social treatment of a few women, whowear a head scarf, within the college/university environment. The study examines socialtreatment from teachers as well as from fellow students. To examine this, the study usesqualitative interviews. The results of the interviews showed that the respondents havevery different experiences. A few of the respondents have very negative experiencesconcerning treatment from teachers, others describe the teachers as supportive.Concerning fellow students some of the respondents described how, in the beginning,they were treated with some distance. This however changed, in most cases, as timewent on. One respondent is undividedly positive about her experience. The studyconcludes that there are examples of both positive and negative social treatment in thewomen's experiences.

  • 1603. Aharonian, F. et al
    et al.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Astronomy.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Meurer, Christine
    Stockholm University, Faculty of Science, Department of Physics.
    Sellerholm, Alexander
    Stockholm University, Faculty of Science, Department of Physics.
    The Fermi/LAT Collaboration,
    Simultaneous Observations of PKS 2155–304 with HESS, Fermi, RXTE, and Atom: Spectral Energy Distributions and Variability in a Low State2009In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 696, no 2, p. L150-L155Article in journal (Refereed)
    Abstract [en]

    We report on the first simultaneous observations that cover the optical, X-ray, and high-energy gamma-ray bands of the BL Lac object PKS 2155–304. The gamma-ray bands were observed for 11 days, between 2008 August 25 and 2008 September 6 (MJD 54704–54715), jointly with the Fermi Gamma-ray Space Telescope and the HESS atmospheric Cherenkov array, providing the first simultaneous MeV-TeV spectral energy distribution (SED) with the new generation of γ-ray telescopes. The ATOM telescope and the RXTE and Swift observatories provided optical and X-ray coverage of the low-energy component over the same time period. The object was close to the lowest archival X-ray and very high energy (VHE; >100 GeV) state, whereas the optical flux was much higher. The light curves show relatively little (~30%) variability overall when compared to past flaring episodes, but we find a clear optical/VHE correlation and evidence for a correlation of the X-rays with the high-energy spectral index. Contrary to previous observations in the flaring state, we do not find any correlation between the X-ray and VHE components. Although synchrotron self-Compton models are often invoked to explain the SEDs of BL Lac objects, the most common versions of these models are at odds with the correlated variability we find in the various bands for PKS 2155–304.

  • 1604. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Bamba, Aya
    Bautz, Marshall W.
    Blandford, Roger
    Brenneman, Laura W.
    Brown, Gregory
    Bulbul, Esra
    Cackett, Edward M.
    Canning, Rebecca E. A.
    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
    Hayashi, Tasuku
    Hayashida, Kiyoshi
    Hiraga, Junko S.
    Hornschemeier, Ann
    Hoshino, Akio
    Hughes, John P.
    Ichinohe, Yuto
    Iizuka, Ryo
    Inoue, Hajime
    Inoue, Shota
    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.
    Lumr, 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, Keigo
    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
    Wang, Qian H. S.
    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
    Atmospheric gas dynamics in the Perseus cluster observed with Hitomi2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 9Article in journal (Refereed)
    Abstract [en]

    Extending the earlier measurements reported in Hitomi collaboration (2016, Nature, 535, 117), we examine the atmospheric gas motions within the central 100 kpc of the Perseus cluster using observations obtained with the Hitomi satellite. After correcting for the point spread function of the telescope and using optically thin emission lines, we find that the line-of-sight velocity dispersion of the hot gas is remarkably low and mostly uniform. The velocity dispersion reaches a maxima of approximately 200 km s(-1) toward the central active galactic nucleus (AGN) and toward the AGN inflated northwestern ghost bubble. Elsewhere within the observed region, the velocity dispersion appears constant around 100 km s(-1). We also detect a velocity gradient with a 100 km s(-1) amplitude across the cluster core, consistent with large-scale sloshing of the core gas. If the observed gas motions are isotropic, the kinetic pressure support is less than 10% of the thermal pressure support in the cluster core. The well-resolved, optically thin emission lines have Gaussian shapes, indicating that the turbulent driving scale is likely below 100 kpc, which is consistent with the size of the AGN jet inflated bubbles. We also report the first measurement of the ion temperature in the intracluster medium, which we find to be consistent with the electron temperature. In addition, we present a new measurement of the redshift of the brightest cluster galaxy NGC 1275.

  • 1605. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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
    Furukawa, Maki
    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
    Kato, Yuichi
    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
    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
    Temperature structure in the Perseus cluster core observed with Hitomi2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 11Article in journal (Refereed)
    Abstract [en]

    The present paper explains the temperature structure of X-ray emitting plasma in the core of the Perseus cluster based on 1.8-20.0 keV data obtained with the Soft X-ray Spectrometer (SXS) on board the Hitomi Observatory. A series of four observations was carried out, with a total effective exposure time of 338 ks that covered a central region of similar to 7' in diameter. SXS was operated with an energy resolution of similar to 5 eV (full width at half maximum) at 5.9 keV. Not only fine structures of K-shell lines in He-like ions, but also transitions from higher principal quantum numbers were clearly resolved from Si through Fe. That enabled us to perform temperature diagnostics using the line ratios of Si, S, Ar, Ca, and Fe, and to provide the first direct measurement of the excitation temperature and ionization temperature in the Perseus cluster. The observed spectrum is roughly reproduced by a single-temperature thermal plasma model in collisional ionization equilibrium, but detailed line-ratio diagnostics reveal slight deviations from this approximation. In particular, the data exhibit an apparent trend of increasing ionization temperature with the atomic mass, as well as small differences between the ionization and excitation temperatures for Fe, the only element for which both temperatures could be measured. The best-fit two-temperature models suggest a combination of 3 and 5 keV gas, which is consistent with the idea that the observed small deviations from a single-temperature approximation are due to the effects of projecting the known radial temperature gradient in the cluster core along the line of sight. A comparison with the Chandra/ACIS and the XMM-Newton/RGS results, on the other hand, suggests that additional lower-temperature components are present in the intracluster medium (ICM), but not detectable with Hitomi/SXS giving its 1.8-20 keV energy band.

  • 1606. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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
    Furukawa, Maki
    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
    Ogorzalek, Anna
    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
    Measurements of resonant scattering in the Perseus Cluster core with Hitomi SXS2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 10Article in journal (Refereed)
    Abstract [en]

    Thanks to its high spectral resolution (similar to 5 eV at 6 keV), the Soft X-ray Spectrometer (SXS) on board Hitomi enables us to measure the detailed structure of spatially resolved emission lines from highly ionized ions in galaxy clusters for the first time. In this series of papers, using the SXS we have measured the velocities of gas motions, metallicities and the multi-temperature structure of the gas in the core of the Perseus Cluster. Here, we show that when inferring physical properties from line emissivities in systems like Perseus, the resonant scattering effect should be taken into account. In the Hitomi waveband, resonant scattering mostly affects the Fe XXV He alpha line (w)-the strongest line in the spectrum. The flux measured by Hitomi in this line is suppressed by a factor of similar to 1.3 in the inner similar to 30 kpc, compared to predictions for an optically thin plasma; the suppression decreases with the distance from the center. The w line also appears slightly broader than other lines from the same ion. The observed distortions of the w line flux, shape, and distance dependence are all consistent with the expected effect of the resonant scattering in the Perseus core. By measuring the ratio of fluxes in optically thick (w) and thin (Fe XXV forbidden, He beta, Ly alpha) lines, and comparing these ratios with predictions from Monte Carlo radiative transfer simulations, the velocities of gas motions have been obtained. The results are consistent with the direct measurements of gas velocities from line broadening described elsewhere in this series, although the systematic and statistical uncertainties remain significant. Further improvements in the predictions of line emissivities in plasma models, and deeper observations with future X-ray missions offering similar or better capabilities to the Hitomi SXS, will enable resonant scattering measurements to provide powerful constraints on the amplitude and anisotropy of cluster gas motions.

  • 1607. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 spectrometer2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 14Article in journal (Refereed)
    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.

  • 1608. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 Hitomi2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 12Article in journal (Refereed)
    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.

  • 1609. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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
    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
    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
    Uno, Shinichiro
    Ueda, Yoshihiro
    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
    Sato, Toshiki
    Nakaniwa, Nozomu
    Murakami, Hiroaki
    Guest, Benson
    Hitomi X-ray observation of the pulsar wind nebula G21.5-0.92018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 3, article id 38Article in journal (Refereed)
    Abstract [en]

    We present results from the Hitomi X-ray observation of a young composite-type supernova remnant (SNR) G21.5-0.9, whose emission is dominated by the pulsar wind nebula (PWN) contribution. The X-ray spectra in the 0.8-80 keV range obtained with the Soft X-ray Spectrometer (SXS), Soft X-ray Imager, and Hard X-ray Imager (HXI) show a significant break in the continuum as previously found with the NuSTAR observation. After taking into account all known emissions from the SNR other than the PWN itself, we find that the Hitomi spectra can be fitted with a broken power law with photon indices of Gamma(1) = 1.74 +/- 0.02 and Gamma(2) = 2.14 +/- 0.01 below and above the break at 7.1 +/- 0.3 keV, which is significantly lower than the NuSTAR result (similar to 9.0 keV). The spectral break cannot be reproduced by time-dependent particle injection one-zone spectral energy distribution models, which strongly indicates that a more complex emission model is needed, as suggested by recent theoretical models. We also search for narrow emission or absorption lines with the SXS, and perform a timing analysis of PSR J1833-1034 with the HXI and the Soft Gamma-ray Detector. No significant pulsation is found from the pulsar. However, unexpectedly, narrow absorption line features are detected in the SXS data at 4.2345 keV and 9.296 keV with a significance of 3.65 sigma. While the origin of these features is not understood, their mere detection opens up a new field of research and was only possible with the high resolution, sensitivity, and ability to measure extended sources provided by an X-ray microcalorimeter.

  • 1610. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 ejecta2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 16Article in journal (Refereed)
    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.

  • 1611. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 pulsar2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 15Article in journal (Refereed)
    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.

  • 1612. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 nucleus2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 13Article in journal (Refereed)
    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.

  • 1613. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 Hitomi2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 2, article id 17Article in journal (Refereed)
    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.

  • 1614. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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
    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
    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
    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
    Uchida, Yuusuke
    Detection of polarized gamma-ray emission from the Crab nebula with the Hitomi Soft Gamma-ray Detector2018In: Publications of the Astronomical Society of Japan, ISSN 0004-6264, E-ISSN 2053-051X, Vol. 70, no 6, article id psy113Article in journal (Refereed)
    Abstract [en]

    We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray / gamma-ray sources on the sky, and, the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed the data analysis of the SGD observation, the SGD background estimation and the SGD Monte Carlo simulations, and, successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% +/- 10.6%), and, the polarization angle is 110.degrees 7 + 13.degrees 2 /-13.degrees 0 in the energy range of 60-160 keV (The errors correspond to the 1 sigma deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, 124.degrees 0 +/- 0.degrees 1.

  • 1615. Aharonian, Felix
    et al.
    Akamatsu, Hiroki
    Akimoto, Fumie
    Allen, Steven W.
    Angelini, Lorella
    Audard, Marc
    Awaki, Hisamitsu
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (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 cluster2017In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 551, no 7681, p. 478-+Article in journal (Refereed)
    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).

  • 1616. Ah-King, M
    et al.
    Elofsson, Helena
    Stockholm University, Faculty of Science, Department of Zoology.
    Kvarnemo, C
    Rosenquist, G
    Berglund, A
    Why no sperm competition in pipefish with externally brooding males?Manuscript (Other academic)
  • 1617.
    Ah-King, Malin
    Stockholm University, Faculty of Humanities, Department of Ethnology, History of Religions and Gender Studies, Gender Studies.
    Flexible Mate Choice2019In: Encyclopedia of Animal Behavior / [ed] Jae Chun Choe, Elsevier, 2019, 2, p. 421-431Chapter in book (Refereed)
    Abstract [en]

    Traditionally, investigators and theorists have supposed that mate choice is directional and fixed within a species as well as static within individuals over time. Lately, accumulating evidence shows that mate choice is often flexible, so that individuals change their behavior, depending on the social or ecological situation they experience or their condition. Recent theory proposes that animals should change their mate choice adaptively moment by moment in response to changes in environmental, internal, and social factors. Mate choice plasticity should be explored more in empirical studies as well as its implications for mate choice evolution and sexual selection.

  • 1618. Ah-King, Malin
    Phylogenetic analyses of parental care evolution2003Doctoral thesis, comprehensive summary (Other academic)
  • 1619.
    Ah-King, Malin
    Stockholm University, Faculty of Humanities, Department of Ethnology, History of Religions and Gender Studies, Gender Studies.
    Queering biology teaching2016In: Queering MINT: Impulse für eine dekonstruktive Lehrer_innenbildung / [ed] Nadine Balzter, Florian Cristobal Klenk, Olga Zitzelsberger, Verlag Barbara Budrich, 2016Chapter in book (Other academic)
  • 1620.
    Ah-King, Malin
    et al.
    Stockholm University, Faculty of Humanities, Department of Ethnology, History of Religions and Gender Studies. Uppsala University, Sweden; University of California, USA.
    Gowaty, Patricia Adair
    A conceptual review of mate choice: stochastic demography, within-sex phenotypic plasticity, and individual flexibility2016In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 6, no 14, p. 4607-4642Article, review/survey (Refereed)
    Abstract [en]

    Mate choice hypotheses usually focus on trait variation of chosen individuals. Recently, mate choice studies have increasingly attended to the environmental circumstances affecting variation in choosers' behavior and choosers' traits. We reviewed the literature on phenotypic plasticity in mate choice with the goal of exploring whether phenotypic plasticity can be interpreted as individual flexibility in the context of the switch point theorem, SPT (Gowaty and Hubbell ). We found >3000 studies; 198 were empirical studies of within-sex phenotypic plasticity, and sixteen showed no evidence of mate choice plasticity. Most studies reported changes from choosy to indiscriminate behavior of subjects. Investigators attributed changes to one or more causes including operational sex ratio, adult sex ratio, potential reproductive rate, predation risk, disease risk, chooser's mating experience, chooser's age, chooser's condition, or chooser's resources. The studies together indicate that choosiness of potential mates is environmentally and socially labile, that is, induced - not fixed - in the choosy sex with results consistent with choosers' intrinsic characteristics or their ecological circumstances mattering more to mate choice than the traits of potential mates. We show that plasticity-associated variables factor into the simpler SPT variables. We propose that it is time to complete the move from questions about within-sex plasticity in the choosy sex to between- and within-individual flexibility in reproductive decision-making of both sexes simultaneously. Currently, unanswered empirical questions are about the force of alternative constraints and opportunities as inducers of individual flexibility in reproductive decision-making, and the ecological, social, and developmental sources of similarities and differences between individuals. To make progress, we need studies (1) of simultaneous and symmetric attention to individual mate preferences and subsequent behavior in both sexes, (2) controlled for within-individual variation in choice behavior as demography changes, and which (3) report effects on fitness from movement of individual's switch points.

  • 1621.
    Ah-King, Malin
    et al.
    Stockholm University, Faculty of Humanities, Department of Ethnology, History of Religions and Gender Studies, Gender Studies.
    Hayward, Eva
    Toxic Sexes: Perverting Pollution and Queering Hormone Disruption2019In: Technosphere magazine, no March 20Article in journal (Refereed)
    Abstract [en]

    What cultural nerves are triggered by the mutations of sexed biologies associated with artificially produced hormones? Evolutionary biologist and gender studies scholar Malin Ah-King and gender studies scholar Eva Hayward question the essentialist and heteronormative assumptions that frame contemporary discourses on the toxicity of endocrine disruptors.

  • 1622. Ah-King, Malin
    et al.
    Nylin, Sören
    Stockholm University, Faculty of Science, Department of Zoology.
    Sex in an Evolutionary Perspective: Just Another Reaction Norm2010In: Evolutionary biology, ISSN 0071-3260, E-ISSN 1934-2845, Vol. 37, no 4, p. 234-246Article, review/survey (Refereed)
    Abstract [en]

    It is common to refer to all sorts of clear-cut differences between the sexes as something that is biologically almost inevitable. Although this does not reflect the status of evolutionary theory on sex determination and sexual dimorphism, it is probably a common view among evolutionary biologists as well, because of the impact of sexual selection theory. To get away from thinking about biological sex and traits associated with a particular sex as something static, it should be recognized that in an evolutionary perspective sex can be viewed as a reaction norm, with sex attributes being phenotypically plastic. Sex determination itself is fundamentally plastic, even when it is termed "genetic". The phenotypic expression of traits that are statistically associated with a particular sex always has a plastic component. This plasticity allows for much more variation in the expression of traits according to sex and more overlap between the sexes than is typically acknowledged. Here we review the variation and frequency of evolutionary changes in sex, sex determination and sex roles and conclude that sex in an evolutionary time-frame is extremely variable. We draw on recent findings in sex determination mechanisms, empirical findings of morphology and behaviour as well as genetic and developmental models to explore the concept of sex as a reaction norm. From this point of view, sexual differences are not expected to generally fall into neat, discrete, pre-determined classes. It is important to acknowledge this variability in order to increase objectivity in evolutionary research.

  • 1623. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School, Management & Organisation.
    Pettersson, Katarina
    Sköld, Birgitta
    Tillmar, Malin
    Entrepreneurship in rural areas: The role of women?2017Conference paper (Refereed)
  • 1624. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School, Management & Organisation.
    Pettersson, Katarina
    Tillmar, Malin
    Can government support both women and entrepreneurship?2014Conference paper (Other academic)
  • 1625. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School, Management & Organisation.
    Pettersson, Katarina
    Tillmar, Malin
    Entrepreneurship for equality?2013Conference paper (Other academic)
  • 1626. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    Pettersson, Katarina
    Tillmar, Malin
    From feminism to FemInc.ism: On the uneasy relationship between feminism, entrepreneurship and the Nordic welfare state2016In: The International Entrepreneurship and Management Journal, ISSN 1554-7191, E-ISSN 1555-1938, Vol. 12, no 2, p. 369-392Article in journal (Refereed)
    Abstract [en]

    Feminism in the Nordic countries was primarily formulated in terms of ‘state feminism’. The women’s movement cooperated with feminist government officials and politicians, resulting in societies that can be considered to be the most gender-equal societies in the world. Historically, the state provided for a large publicly-financed welfare sector which made it possible for many women to combine work and family through the state’s implementation of family-friendly policies, while simultaneously providing employment opportunities for many women. However, since the financial crisis of the 1990s, there has been a political change influenced by neo-liberal thought, in which politicians have handed over the welfare state’s responsibilities to the market, and, instead, the politicians have encouraged entrepreneurship, not least among women. Further to this development, there has been a change in emphasis from entrepreneurship (understood as starting and running a business) to entrepreneurialism which, in addition to a belief in the efficacy of market forces, also contains a social dimension where individuals are supposed to be flexible and exercise choice. In this article, we ask whether this entails a change in the feminist project in the Nordic countries, and if so, what the likely consequences are for this project, both in practice and in research. In order to answer this question, we reviewed existing Nordic research on women’s entrepreneurship and examined how this body of work conceptualizes entrepreneurship, gender, the state, and equality. We also considered whether any trends could be identified. We relate our findings to recent changes in government policy and conclude that the current discourse on entrepreneurship challenges, and possibly weakens, state feminism, but we also conclude that this discourse may also provide space for new forms of feminist action, in market terms. We coin the term FemInc.ism to denote feminist action through enterprise and we discuss a number of important challenges that research on this phenomenon is faced with.

  • 1627. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School, Management & Organisation.
    Pettersson, Katarina
    Tillmar, Malin
    Is institutional support for women’s entrepreneurship feminist?2014In: GWO2014 Book of abstracts: GWO 8th Biennial International Interdisciplinary conference, Wiley-Blackwell, 2014Conference paper (Other academic)
  • 1628. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School.
    Pettersson, Katarina
    Tillmar, Malin
    Will business ownership support gender equality?2012Conference paper (Other academic)
  • 1629. Ahl, Helene
    et al.
    Berglund, Karin
    Stockholm University, Faculty of Social Sciences, Stockholm Business School, Management & Organisation.
    Pettersson, Katarina
    Tillmar, Malin
    Women’s entrepreneurship in rural areas: A literature review.2017Conference paper (Other academic)
  • 1630. Ahl, Helene
    et al.
    Bergmo-Prvulovic, IngelaStockholm University, Faculty of Social Sciences, Department of Education.Kilhammar, Karin
    HR: Att ta tillvara mänskliga resurser2017Collection (editor) (Other academic)
  • 1631.
    Ahl, Joel
    Stockholm University, Faculty of Law, Department of Law.
    Provokativa åtgärder: en balansakt2014Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
  • 1632. Ahlandsberg, Staffan
    Metabolic engineering of starch synthesis in barley2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Starch is an important industrial raw material both for food and non-food purposes. In plants, starch is deposited in the leaf and in the storage tissues such as seed endosperm, roots or tubers. Starch is a glucose polymer, and its synthesis involves four groups of enzymes, ADP-glucose-pyrophosphorylase (AGPase), starch synthases (SS), starch branching enzymes (SBE), and starch debranching enzymes (DBE). In barley, four isoforms of SBE have been identified and the temporal and spatial expression of their genes (sbe) has been studied in our lab.

    The long-term objective of our research is to produce novel starches in planta for industrial applications. This requires the transformation of barley in order to produce transgenic plants with altered activity for one or more sbe genes. Using a plant-optimized version of Green Fluorescent Protein (GFP) as the only marker we produced a transgenic Nordic elite cultivar of barley in 1999. The usefulness of GFP as a marker has also been applied in various transient experiments and for this reason a set of monocotyledonous expression vectors has been developed. Using these vectors, the spatial expression pattern of the sbeII genes has been investigated.

    The sbeIIa and sbeIIb genes are differentially transcribed during barley seed development. The sbeIIb gene is expressed exclusively in the endosperm while the sbeIIa gene is expressed also in embryonic and vegetative tissues. The tissue specific regulation of the sbeII genes was hown to be executed via a repressor protein acting on a cis element located in the second intron of the sbeIIb gene. We also suggest that the repression is controlled by the local sugar concentration in the barley seed endosperm.

  • 1633.
    Ahlbeck, Bengt
    Stockholm University.
    Musikdirektör Anders Sidner: Musikundervisning och musikliv i skolstaden Härnösand 1840-18701998Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The present study, together with my licentiate's dissertation, Music education and examination at the Royal Academy of Music during "the Pehr Frigel Era", 1796-1842, constitutes my doctoral dissertation. In the chapter Preludes, the relation between the two studies is accounted for.

    The study deals with Anders Sidner's work and career, and his influence on the teaching of music and music life in Härnösand. In my licentiate's dissertation I examined the music education and examination at the Royal Academy of Music during the first half of the nineteenth century. I pointed out, from a cultural-theoretical perspective, that the work of the Academy probably promoted cultural solidarity in a socially developing manner. Anders Sidner was one of around eighty graduates who were examined during this period. The aim of this study is to map out and critically examine Sidner's work and career in Härnösand, as well as to observe what effects his work has had.

    The structure of the study is mainly chronological. The understanding of Sidner's work, ideas and actions is based to a great extent on the knowledge of his personal situation and living conditions.

    Sidner's music studies, which were pursued parallel with his academic studies at Uppsala, are characterised by self-tuition, learning from friends and active participation in choirs and orchestras.

    After his academic studies at Uppsala and the graduation from the Royal Academy of Music, Sidner worked in Härnösand for twenty-eight years as a music teacher at grammar school and teacher training college. In both types of education, choir singing was an important part of the teaching. Sidner took the initiative in founding a musical society, and was its leader for a number of years. In the 1860s he initiated a collaboration between the musical society and a great number of the town's young male and female musicians. Sidner also engaged young female instrumentalists in the student orchestra. Both these initiatives can be considered unique.

    In relation to the town population, a remarkably great number of people attended the wide variety of musical events. The fact that the school's spacious music hall was used as a concert hall and that the music teacher as well as a number of other teachers were active in the local music life probably contributed to the active participation of many young people.

    The examination of Anders Sidner's teaching methods and his ideas on musical-aesthetic issues shows that his work was in line with the widely spread values of his time.

    My study indicates that Sidner's contribution to the teaching of music and music life in Härnösand promoted an increasing cultural solidarity. It is evident that his work also was to form part of a continuous process of secularisation. The music life in school was integrated with non-ecclesiastical activities to an ever increasing extent.

  • 1634.
    Ahlbeck Bergendahl, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Salvanes, Anne Gro V.
    Braithwaite, Victoria A.
    Determining the effects of duration and recency of exposure to environmental enrichment2016In: Applied Animal Behaviour Science, ISSN 0168-1591, E-ISSN 1872-9045, Vol. 176, p. 163-169Article in journal (Refereed)
    Abstract [en]

    Experience can help animals adapt their behaviour to fit the environment or conditions that they find themselves in. Understanding how and when experience affects behaviour is important for the animals we rear in captivity. This is particularly true when we rear animals with the intent of releasing them into the wild as part of population rehabilitation and conservation efforts. We investigated how exposure to a changing, more complex environment promotes behavioural development in juvenile trout. Four groups of fish were compared; (i) fish that were maintained without enrichment, (ii) fish that were exposed to an early period of enrichment, but were then returned to a plain environment, (iii) fish that were maintained in plain conditions, but were then exposed to enrichment towards the end of the rearing phase, (iv) a group that were kept in enriched conditions throughout the 12 week rearing period. We then assessed fish anxiety levels, their spatial learning ability, and the capacity of the fish to find their way through a barrier where different routes were presented across 4 different trials. Fish that experienced enriched conditions for the longest duration had superior spatial learning abilities, and they were better at finding the correct route to get past the barrier than fish from the remaining three treatments. Positive effects on behaviour were, however, also found in the fish that only experienced enrichment in the last part of the rearing period, compared to the control, or fish exposed to early enrichment. No effect of enrichment was found on levels of anxiety in any of the groups.

  • 1635.
    Ahlbeck, Ida
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Living in a predation matrix: Studies on fish and their prey in a Baltic Sea coastal area2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis was written within the framework of a biomanipulation project where young-of-the-year (YOY) pikeperch (Sander lucioperca) were stocked to a Baltic Sea bay to improve water quality through a top-down trophic cascade. The aim of my doctorial studies was however focused on a broader ecological question, namely predation (the main driving force in a biomanipulation). Hence, this thesis consists of four papers where we study the interactions between predator and prey using fish and zooplankton and how these interactions can be measured.

    In paper I we evaluated the performance of different diet analysis methods by individual based modelling and found that when having a nutritional gain perspective, mass based methods described diets best. Paper II investigated how the explorative, foraging and anti-predator behaviour of the YOY pikeperch used for stocking were affected by their rearing environment (pond vs. tank rearing). The more complex and varied environment in the semi-natural ponds seemed to promote a more flexible and active behaviour, better equipping young fish for survival in the wild. For paper III we studied the diel vertical migration in the six copepodite stages of the zooplankton Acartia spp. and Eurytemora affinis in relation to fish biomass, phytoplankton abundance and temperature. Both species migrated and in addition showed increased migration range with size within species, indicating evasion from visual predators. Paper IV addressed the movement of littoral Eurasian perch (Perca fluviatilis) via stable isotope signatures (13C and 15N) and body condition. We found clear indications of sedentarity and intra-habitat dietary differences. Interactions between predators and prey are complex and affected by both physiological and environmental characteristics as well as behavioural traits. The results in this thesis suggest that different species and even different life stages pursue different strategies to survive.

  • 1636.
    Ahlbeck, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hjerne, Olle
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Evaluating fish diet analysis methods by individual-based modelling2012In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 69, no 7, p. 1184-1201Article in journal (Refereed)
    Abstract [en]

    Knowledge of diet compositions is important in ecological research. There are many methods available and numerous aspects of diet composition. Here we used modelling to evaluate how well different diet analysis methods describe the true diet of fish, expressed in mass percentages. The methods studied were both basic methods (frequency of occurrence, dominance, numeric, mass, points) and composite indices (Index of Relative Importance, Comparative Feeding Index). Analyses were based on both averaged stomach content of individual fish and on pooled content from several fish. Prey preference, prey size, and evacuation rate influenced the performance of the diet analysis methods. The basic methods performed better than composite indices. Mass and points methods produced diet compositions most similar to the true diet and were also most robust, indicating that these methods should be used to describe energetic-nutritional sources of fish.

  • 1637.
    Ahlbeck, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hjerne, Olle
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Evaluation of diet analysis methods by individual based modellingIn: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533Article in journal (Refereed)
  • 1638.
    Ahlbeck, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Hansson, Sture
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Karlöf, Oliver
    Sedentarity in Eurasian perch (Perca fluviatilis) in a coastal Baltic Sea areaIn: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633Article in journal (Refereed)
  • 1639.
    Ahlbeck, Ida
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Holliland, Per B.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Rearing environment affect important life skills in pikeperch (Sander lucioperca)2012In: Boreal environment research, ISSN 1239-6095, E-ISSN 1797-2469, Vol. 17, no 3-4, p. 291-304Article in journal (Refereed)
    Abstract [en]

    The effect of rearing environment on the behaviour of young-of-the-year pikeperch (Sander lucioperca) bred at three different production facilities was investigated. Two groups were reared in semi-natural ponds and one group in indoor tanks. Exploratory, foraging and anti-predator behaviours were studied in aquarium experiments. There were no significant differences between pond- and tank-reared fish in reluctance to explore their new environment, but pond-reared fish spent significantly more time in macro-vegetation. Pond-reared fish were significantly faster to start foraging on live prey (Neomysis integer) that they had not encountered before. As compared with tank-reared fish, pond-reared fish were also significantly more active in their anti-predator response. Rearing environment obviously influences the development of important life skills. These differences may impact the success rate when stocking young-of-the-year pikeperch into natural waters.

  • 1640.
    Ahlbeck, Mattias
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Johansson, Henrik
    Stockholm University, Faculty of Social Sciences, School of Business.
    Internetpoker: En studie i köpbeteendet hos pokerproffs2006Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Arbetet behandlar hypotesen om huruvida personer som har sin primärinkomst från Internetpokerspel har homogena köpvanor eller inte. Med hjälp av konsumentteori och kvalitativa intervjuer med ett antal pokerproffs fösöker denna studie ge svar på detta.

  • 1641. Ahlberg, Alexander
    et al.
    al-Abany, Massoud
    Alevronta, Eleftheria
    Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
    Friesland, Signe
    Hellborg, Henrik
    Mavroidis, Panayiotis
    Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
    Lind, Bengt K.
    Stockholm University, Faculty of Science, Medical Radiation Physics (together with KI).
    Laurell, Göran
    ESOPHAGEAL STRICTURE AFTER RADIOTHERAPY IN PATIENTS WITH HEAD AND NECK CANCER: EXPERIENCE OF A SINGLE INSTITUTION OVER 2 TREATMENT PERIODS2010In: Head and Neck, ISSN 1043-3074, E-ISSN 1097-0347, Vol. 32, no 4, p. 452-461Article in journal (Refereed)
    Abstract [en]

    Background. Risk factors for development of a stricture of the upper esophagus after radiotherapy for head and neck cancer are poorly defined. Methods. This was a retrospective case-control study of patients diagnosed and treated for esophageal stricture after radiotherapy for head and neck cancer. Results. The incidence of esophageal stricture after external beam radiation therapy (EBRT) was 3.3%. Seventy patients with stricture and 66 patients without stricture were identified. A multivariate analysis showed that there was increased risk of stricture in receiving enteral feeding during EBRT or in receiving a mean dose of >45 By to the upper esophagus. Conclusions. Enteral feeding during EBRT is strongly associated with the development of stricture of the esophagus, as is a mean dose of >45 Gy to the upper esophagus. Treatment of the stricture with Savary-Gilliard bougienage or through scope balloon dilatation is safe and successful but often has to be repeated.

  • 1642.
    Ahlberg, Daniel
    Stockholm University, Faculty of Science, Department of Mathematics.
    A temporal perspective on the rate of convergence in first-passage percolation under a moment condition2019In: Brazilian Journal of Probability and Statistics, ISSN 0103-0752, E-ISSN 2317-6199, Vol. 33, no 2, p. 397-401Article in journal (Refereed)
    Abstract [en]

    We study the rate of convergence in the celebrated Shape Theorem in first-passage percolation, obtaining the precise asymptotic rate of decay for the probability of linear order deviations under a moment condition. Our results are presented from a temporal perspective and complement previous work by the same author, in which the rate of convergence was studied from the standard spatial perspective.

  • 1643.
    Ahlberg, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Baldasso, Rangel
    Noise sensitivity and Voronoi percolation2018In: Electronic Journal of Probability, ISSN 1083-6489, E-ISSN 1083-6489, Vol. 23, article id 108Article in journal (Refereed)
    Abstract [en]

    In this paper we study noise sensitivity and threshold phenomena for Poisson Voronoi percolation on R-2. In the setting of Boolean functions, both threshold phenomena and noise sensitivity can be understood via the study of randomized algorithms. Together with a simple discretization argument, such techniques apply also to the continuum setting. Via the study of a suitable algorithm we show that box-crossing events in Voronoi percolation are noise sensitive and present a threshold phenomenon with polynomial window. We also study the effect of other kinds of perturbations, and emphasize the fact that the techniques we use apply for a broad range of models.

  • 1644.
    Ahlberg, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Deijfen, Maria
    Stockholm University, Faculty of Science, Department of Mathematics.
    Janson, Svante
    Competing first passage percolation on random graphs with finite variance degrees2019In: Random structures & algorithms (Print), ISSN 1042-9832, E-ISSN 1098-2418, Vol. 55, no 3, p. 545-559Article in journal (Refereed)
    Abstract [en]

    We study the growth of two competing infection types on graphs generated by the configuration model with a given degree sequence. Starting from two vertices chosen uniformly at random, the infection types spread via the edges in the graph in that an uninfected vertex becomes type 1 (2) infected at rate lambda(1) (lambda(2)) times the number of nearest neighbors of type 1 (2). Assuming (essentially) that the degree of a randomly chosen vertex has finite second moment, we show that if lambda(1) = lambda(2), then the fraction of vertices that are ultimately infected by type 1 converges to a continuous random variable V is an element of (0,1), as the number of vertices tends to infinity. Both infection types hence occupy a positive (random) fraction of the vertices. If lambda(1) not equal lambda(2), on the other hand, then the type with the larger intensity occupies all but a vanishing fraction of the vertices. Our results apply also to a uniformly chosen simple graph with the given degree sequence.

  • 1645.
    Ahlberg, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Griffiths, Simon
    Janson, Svante
    Morris, Robert
    Competition in growth and urns2019In: Random structures & algorithms (Print), ISSN 1042-9832, E-ISSN 1098-2418, Vol. 54, no 2, p. 211-227Article in journal (Refereed)
    Abstract [en]

    We study survival among two competing types in two settings: a planar growth model related to two-neighbor bootstrap percolation, and a system of urns with graph-based interactions. In the planar growth model, uncolored sites are given a color at rate 0, 1 or infinity, depending on whether they have zero, one, or at least two neighbors of that color. In the urn scheme, each vertex of a graph G has an associated urn containing some number of either blue or red balls ( but not both). At each time step, a ball is chosen uniformly at random from all those currently present in the system, a ball of the same color is added to each neighboring urn, and balls in the same urn but of different colors annihilate on a one-for-one basis. We show that, for every connected graph G and every initial configuration, only one color survives almost surely. As a corollary, we deduce that in the two-type growth model on Z(2), one of the colors only infects a finite number of sites with probability one. We also discuss generalizations to higher dimensions and multi-type processes, and list a number of open problems and conjectures.

  • 1646.
    Ahlberg, Daniel
    et al.
    Stockholm University, Faculty of Science, Department of Mathematics.
    Tassion, Vincent
    Teixeira, Augusto
    Existence of an unbounded vacant set for subcritical continuum percolation2018In: Electronic Communications in Probability, ISSN 1083-589X, E-ISSN 1083-589X, Vol. 23, article id 63Article in journal (Refereed)
    Abstract [en]

    We consider the Poisson Boolean percolation model in R-2, where the radius of each ball is independently chosen according to some probability measure with finite second moment. For this model, we show that the two thresholds, for the existence of an unbounded occupied and an unbounded vacant component, coincide. This complements a recent study of the sharpness of the phase transition in Poisson Boolean percolation by the same authors. As a corollary it follows that for Poisson Boolean percolation in R-d, for any d >= 2, finite moment of order d is both necessary and sufficient for the existence of a nontrivial phase transition for the vacant set.

  • 1647.
    Ahlberg, Gösta
    Stockholm College.
    Befolkningsutvecklingen och urbaniseringen i Sverige 1911-19501953Doctoral thesis, monograph (Other academic)
  • 1648.
    Ahlberg, Hjalmar
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Cederhage, Christoffer
    Stockholm University, Faculty of Social Sciences, School of Business.
    Ekström, Jonas
    Stockholm University, Faculty of Social Sciences, School of Business.
    Telekomanalys - modeller och problem2005Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Värderingar av telekombolag under åren 2000 till 2003 har visat sig vara felaktiga främst pga. alltför höga förväntningar på telekommarknaden.

  • 1649.
    Ahlberg, Joakim
    Stockholm University, Faculty of Social Sciences, School of Business.
    Avkastningskrav på aktieplaceringar; vad är rimligt?2002Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vi lever i ett kapitalistiskt system. hela detta system bygger på att avkastningen på det kapital som investerats i systemet skall räcka till att "föda" de personer som ingår i systemet. Investeringar i vår tid har alltmer börjat bli koncentrearade till aktiemarknaden. Härmed har aktievärderingarna skruvats upp mer och mer, och har till sist nått en nivå där den sannolika avkastningen för den som placerar på dessa höga nivåer blir mycket låg.

  • 1650.
    Ahlberg, Joakim
    et al.
    Stockholm University, Faculty of Social Sciences, School of Business.
    Dahlström, Mattias
    Stockholm University, Faculty of Social Sciences, School of Business.
    Aktierekommendationer: -En Jämförande Analys2004Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med denna jämförande studie har varit att undersöka om någon fondkommissionär i vårt urval utfärdar bättre analyser och därmed har ett informationsövertag gentemot övriga, samt i vilken utsträckning det utfärdas sälj- respektive köprekommendationer. Vi har använt oss av olika modeller vilka vi konstruerat själva. Resultatet tyder på en positiv ”bias” då det utfärdas tre gånger fler köprekommendationer än säljrekommendationer. Uppsatsen visar

30313233343536 1601 - 1650 of 109072
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf