Change search
Refine search result
12 1 - 50 of 78
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)
  • 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)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the 'Create feeds' function.
  • 1. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bouvier, A.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Escande, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Fortin, P.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Itoh, R.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Latronico, L.
    Lee, S. -H
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Nishino, S.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Pelassa, V.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Roth, M.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Scargle, J. D.
    Schalk, T. L.
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Tanaka, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Troja, E.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Ziegler, M.
    FERMI GAMMA-RAY SPACE TELESCOPE OBSERVATIONS OF THE GAMMA-RAY OUTBURST FROM 3C454.3 IN NOVEMBER 20102011In: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 733, no 2, L26- p.Article in journal (Refereed)
    Abstract [en]

    The flat-spectrum radio quasar 3C454.3 underwent an extraordinary 5 day gamma-ray outburst in 2010 November when the daily flux measured with the Fermi Large Area Telescope (LAT) at photon energies E > 100 MeV reached (66 +/- 2) x 10(-6) photons cm(-2) s(-1). This is a factor of three higher than its previous maximum flux recorded in 2009 December and greater than or similar to 5 times brighter than the Vela pulsar, which is normally the brightest source in the gamma-ray sky. The 3 hr peak flux was (85 +/- 5) x 10(-6) photons cm-2 s(-1), corresponding to an apparent isotropic luminosity of (2.1 +/- 0.2) x10(50) erg s(-1), the highest ever recorded for a blazar. In this Letter, we investigate the features of this exceptional event in the gamma-ray band of the Fermi-LAT. In contrast to previous flares of the same source observed with the Fermi-LAT, clear spectral changes are observed during the flare.

  • 2. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Antolini, E.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Cannon, A.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Costamante, L.
    Cutini, S.
    Dermer, C. D.
    de Palma, F.
    Donato, D.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Escande, L.
    Favuzzi, C.
    Fegan, S. J.
    Finke, J.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Hughes, R. E.
    Itoh, R.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lee, S. -H
    Garde, Maja Llena
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Makeev, A.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Naumann-Godo, M.
    Nishino, S.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Roth, M.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Sander, A.
    Schinzel, F. K.
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Sokolovsky, K. V.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uehara, T.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wallace, E.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    SUBYang, Z.
    Ylinen, T.
    Ziegler, M.
    Berdyugin, A.
    Boettcher, M.
    Carraminana, A.
    Carrasco, L.
    de la Fuente, E.
    Diltz, C.
    Hovatta, T.
    Kadenius, V.
    Kovalev, Y. Y.
    Lahteenmaki, A.
    Lindfors, E.
    Marscher, A. P.
    Nilsson, K.
    Pereira, D.
    Reinthal, R.
    Roustazadeh, P.
    Savolainen, T.
    Sillanpaa, A.
    Takalo, L. O.
    Tornikoski, M.
    THE FIRST FERMI MULTIFREQUENCY CAMPAIGN ON BL LACERTAE: CHARACTERIZING THE LOW-ACTIVITY STATE OF THE EPONYMOUS BLAZAR2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 730, no 2, 101- p.Article in journal (Refereed)
    Abstract [en]

    We report on observations of BL Lacertae during the first 18 months of Fermi LAT science operations and present results from a 48 day multifrequency coordinated campaign from 2008 August 19 to 2008 October 7. The radio to gamma-ray behavior of BL Lac is unveiled during a low-activity state thanks to the coordinated observations of radio-band (Metsahovi and VLBA), near-IR/optical (Tuorla, Steward, OAGH, and MDM), and X-ray (RXTE and Swift) observatories. No variability was resolved in gamma rays during the campaign, and the brightness level was 15 times lower than the level of the 1997 EGRET outburst. Moderate and uncorrelated variability has been detected in UV and X-rays. The X-ray spectrum is found to be concave, indicating the transition region between the low- and high-energy components of the spectral energy distribution (SED). VLBA observation detected a synchrotron spectrum self-absorption turnover in the innermost part of the radio jet appearing to be elongated and inhomogeneous, and constrained the average magnetic field there to be less than 3 G. Over the following months, BL Lac appeared variable in gamma rays, showing flares (in 2009 April and 2010 January). There is no evidence for the correlation of gamma rays with the optical flux monitored from the ground in 18 months. The SED may be described by a single-zone or a two-zone synchrotron self-Compton (SSC) model, but a hybrid SSC plus external radiation Compton model seems to be preferred based on the observed variability and the fact that it provides a fit closest to equipartition.

  • 3. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Atwoo, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Bouvier, A.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Silva, E. do Couto E
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Fortin, P.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hays, E.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Iafrate, G.
    Jackson, M. S.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Poon, H.
    Porter, T. A.
    Prokhorov, D.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Rochester, L. S.
    Roth, M.
    Sadrozinski, H. F. -W
    Sanchez, D. A.
    Sbarra, C.
    Schalk, T. L.
    Sgro, C.
    Share, G. H.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Stawarz, L.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, D. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    FERMI OBSERVATIONS OF gamma-RAY EMISSION FROM THE MOON2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 758, no 2, 140- p.Article in journal (Refereed)
    Abstract [en]

    We report on the detection of high-energy gamma-ray emission from the Moon during the first 24 months of observations by the Fermi Large Area Telescope (LAT). This emission comes from particle cascades produced by cosmic-ray (CR) nuclei and electrons interacting with the lunar surface. The differential spectrum of the Moon is soft and can be described as a log-parabolic function with an effective cutoff at 2-3 GeV, while the average integral flux measured with the LAT from the beginning of observations in 2008 August to the end of 2010 August is F(> 100 MeV) = (1.04 +/- 0.01 [statistical error] +/- 0.1 [systematic error]) x 10(-6) cm(-2) s(-1). This flux is about a factor 2-3 higher than that observed between 1991 and 1994 by the EGRET experiment on board the Compton Gamma Ray Observatory, F(> 100 MeV) approximate to 5 x 10(-7) cm-2 s-1, when solar activity was relatively high. The higher gamma-ray flux measured by Fermi is consistent with the deep solar minimum conditions during the first 24 months of the mission, which reduced effects of heliospheric modulation, and thus increased the heliospheric flux of Galactic CRs. A detailed comparison of the light curve with McMurdo Neutron Monitor rates suggests a correlation of the trends. The Moon and the Sun are so far the only known bright emitters of gamma-rays with fast celestial motion. Their paths across the sky are projected onto the Galactic center and high Galactic latitudes as well as onto other areas crowded with high-energy gamma-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

  • 4. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bouvier, A.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Cannon, A.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Celik, Oe.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Costamante, L.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Frailis, M.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Guiriec, S.
    Hayashida, M.
    Hays, E.
    Hill, A. B.
    Horan, D.
    Hughes, R. E.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy.
    Latronico, L.
    Lemoine-Goumard, M.
    Garde, Maja Llena
    Stockholm University, Faculty of Science, Department of Physics.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Mansutti, O.
    Massaro, E.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Meurer, C.
    Stockholm University, Faculty of Science, Department of Physics.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Rodriguez, A. Y.
    Romani, R. W.
    Roth, M.
    Ryde, F.
    Sadrozinski, H. F. -W
    Sander, A.
    Scargle, J. D.
    Schalk, T. L.
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Strickman, M. S.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vasileiou, V.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Wehrle, A. E.
    Winer, B. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Ylinen, T.
    Ziegler, M.
    FERMI-LARGE AREA TELESCOPE OBSERVATIONS OF THE EXCEPTIONAL GAMMA-RAY OUTBURSTS OF 3C 273 IN 2009 SEPTEMBER2010In: The Astrophysical Journal Letters, ISSN 2041-8205, Vol. 714, no 1, L73-L78 p.Article in journal (Refereed)
    Abstract [en]

    We present the light curves and spectral data of two exceptionally luminous gamma-ray outbursts observed by the Large Area Telescope experiment on board the Fermi Gamma-ray Space Telescope from 3C 273 in 2009 September. During these flares, having a duration of a few days, the source reached its highest gamma-ray flux ever measured. This allowed us to study, in some details, their spectral and temporal structures. The rise and the decay are asymmetric on timescales of 6 hr, and the spectral index was significantly harder during the flares than during the preceding 11 months. We also found that short, very intense flares put out the same time-integrated energy as long, less intense flares like that observed in 2009 August.

  • 5. Abdo, A. A.
    et al.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Belfiore, A.
    Bellazzini, R.
    Bhattacharyya, B.
    Bissaldi, E.
    Bloom, E. D.
    Bonamente, E.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burgay, M.
    Burnett, T. H.
    Busetto, G.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Camilo, F.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe .
    Charles, E.
    Chaty, S.
    Chaves, R. C. G.
    Chekhtman, A.
    Chen, A. W.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cognard, I.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    De Angelis, A.
    DeCesar, M. E.
    De Luca, A.
    Den Hartog, P. R.
    De Palma, F.
    Dermer, C. D.
    Desvignes, G.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Dumora, D.
    Espinoza, C. M.
    Falletti, L.
    Favuzzi, C.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Freire, P. C. C.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gotthelf, E. V.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hessels, J.
    Hewitt, J.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Jackson, M. S.
    Janssen, G. H.
    Jogler, T.
    Johannesson, G.
    Johnson, R. P.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Johnston, S.
    Kamae, T.
    Kataoka, J.
    Keith, M.
    Kerr, M.
    Knoedlseder, J.
    Kramer, M.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Lyne, A. G.
    Manchester, R. N.
    Marelli, M.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    McLaughlin, M. A.
    Mehault, J.
    Michelson, P. F.
    Mignani, R. P.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Pletsch, H. J.
    Porter, T. A.
    Possenti, A.
    Raino, S.
    Rando, R.
    Ransom, S. M.
    Ray, P. S.
    Razzano, M.
    Rea, N.
    Reimer, A.
    Reimer, O.
    Renault, N.
    Reposeur, T.
    Ritz, S.
    Romani, R. W.
    Roth, M.
    Rousseau, R.
    Roy, J.
    Ruan, J.
    Sartori, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schulz, A.
    Sgro, C.
    Shannon, R.
    Siskind, E. J.
    Smith, D. A.
    Spandre, G.
    Spinelli, P.
    Stappers, B. W.
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Theureau, G.
    Thompson, D. J.
    Thorsett, S. E.
    Tibaldo, L.
    Tibolla, O.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Venter, C.
    Vianello, G.
    Vitale, V.
    Wang, N.
    Weltevrede, P.
    Winer, B. L.
    Wolff, M. T.
    Wood, D. L.
    Wood, K. S.
    Wood, M.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    THE SECOND FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS2013In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 208, no 2Article in journal (Refereed)
    Abstract [en]

    This catalog summarizes 117 high-confidence >= 0.1 GeV gamma-ray pulsar detections using three years of data acquired by the Large Area Telescope (LAT) on the Fermi satellite. Half are neutron stars discovered using LAT data through periodicity searches in gamma-ray and radio data around LAT unassociated source positions. The 117 pulsars are evenly divided into three groups: millisecond pulsars, young radio-loud pulsars, and young radio-quiet pulsars. We characterize the pulse profiles and energy spectra and derive luminosities when distance information exists. Spectral analysis of the off-peak phase intervals indicates probable pulsar wind nebula emission for four pulsars, and off-peak magnetospheric emission for several young and millisecond pulsars. We compare the gamma-ray properties with those in the radio, optical, and X-ray bands. We provide flux limits for pulsars with no observed gamma-ray emission, highlighting a small number of gamma-faint, radio-loud pulsars. The large, varied gamma-ray pulsar sample constrains emission models. Fermi's selection biases complement those of radio surveys, enhancing comparisons with predicted population distributions.

  • 6. Acero, F.
    et al.
    Ackermann, M.
    Ajello, M.
    Albert, A.
    Atwood, W. B.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Belfiore, A.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bogart, J. R.
    Bonino, R.
    Bottacini, E.
    Bregeon, J.
    Britto, R. J.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Science, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    DeKlotz, M.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Iafrate, G.
    Jogler, T.
    Johannesson, G.
    Johnson, R. P.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Katsuta, J.
    Kuss, M.
    La Mura, G.
    Landriu, D.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Li, J.
    Li, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mirabal, N.
    Mizuno, T.
    Moiseev, A. A.
    Mongelli, M.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Racusin, J. L.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Rochester, L. S.
    Romani, R. W.
    Salvetti, D.
    Sanchez-Coude, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Parkinson, P. M. Saz
    Schulz, A.
    Siskind, E. J.
    Smith, D. A.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Stephens, T. E.
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Torresi, E.
    Tosti, G.
    Troja, E.
    Van Klaveren, B.
    Vianello, G.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    FERMI LARGE AREA TELESCOPE THIRD SOURCE CATALOG2015In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 218, no 2, 23Article in journal (Refereed)
    Abstract [en]

    We present the third Fermi Large Area Telescope (LAT) source catalog (3FGL) of sources in the 100 MeV-300 GeV range. Based on the first 4 yr of science data from the Fermi Gamma-ray Space Telescope mission, it is the deepest yet in this energy range. Relative to the Second Fermi LAT catalog, the 3FGL catalog incorporates twice as much data, as well as a number of analysis improvements, including improved calibrations at the event reconstruction level, an updated model for Galactic diffuse.-ray emission, a refined procedure for source detection, and improved methods for associating LAT sources with potential counterparts at other wavelengths. The 3FGL catalog includes 3033 sources above 4 sigma significance, with source location regions, spectral properties, and monthly light curves for each. Of these, 78 are flagged as potentially being due to imperfections in the model for Galactic diffuse emission. Twenty-five sources are modeled explicitly as spatially extended, and overall 238 sources are considered as identified based on angular extent or correlated variability (periodic or otherwise) observed at other wavelengths. For 1010 sources we have not found plausible counterparts at other wavelengths. More than 1100 of the identified or associated sources are active galaxies of the blazar class; several other classes of non-blazar active galaxies are also represented in the 3FGL. Pulsars represent the largest Galactic source class. From source counts of Galactic sources we estimate that the contribution of unresolved sources to the Galactic diffuse emission is similar to 3% at 1 GeV.

  • 7. Acero, F.
    et al.
    Ackermann, M.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    Dalton, M.
    D'Ammando, F.
    de Palma, F.
    Dermer, C. D.
    Di Venere, L.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Falletti, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gregoire, T.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hayashi, K.
    Hays, E.
    Hewitt, J.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    SUBJackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kawano, T.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Marelli, M.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Roth, M.
    Rousseau, R.
    Parkinson, P. M. Saz
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Takahashi, H.
    Takeuchi, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    CONSTRAINTS ON THE GALACTIC POPULATION OF TeV PULSAR WIND NEBULAE USING FERMI LARGE AREA TELESCOPE OBSERVATIONS2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 773, no 1, 77- p.Article in journal (Refereed)
    Abstract [en]

    Pulsar wind nebulae (PWNe) have been established as the most populous class of TeV gamma-ray emitters. Since launch, the Fermi Large Area Telescope (LAT) has identified five high-energy (100 MeV < E < 100 GeV) gamma-ray sources as PWNe and detected a large number of PWN candidates, all powered by young and energetic pulsars. The wealth of multi-wavelength data available and the new results provided by Fermi-LAT give us an opportunity to find new PWNe and to explore the radiative processes taking place in known ones. The TeV gamma-ray unidentified (UNID) sources are the best candidates for finding new PWNe. Using 45 months of Fermi-LAT data for energies above 10 GeV, an analysis was performed near the position of 58 TeV PWNe and UNIDs within 5. of the Galactic plane to establish new constraints on PWN properties and find new clues on the nature of UNIDs. Of the 58 sources, 30 were detected, and this work provides their gamma-ray fluxes for energies above 10 GeV. The spectral energy distributions and upper limits, in the multi-wavelength context, also provide new information on the source nature and can help distinguish between emission scenarios, i.e., between classification as a pulsar candidate or as a PWN candidate. Six new GeV PWN candidates are described in detail and compared with existing models. A population study of GeV PWN candidates as a function of the pulsar/PWN system characteristics is presented.

  • 8. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Allafort, A.
    Antolini, E.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Bottacini, E.
    Bouvier, A.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad,
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Acad Sci, Stockholm, Sweden.
    Cutini, S.
    Dalton, M.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M-H
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hewitt, J.
    Hill, A. B.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    Jackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Kawano, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Romoli, C.
    Roth, M.
    Sanchez-Conde, M.
    Scargle, J. D.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Takahashi, H.
    Takeuchi, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Tronconi, V.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    THE FERMI ALL-SKY VARIABILITY ANALYSIS: A LIST OF FLARING GAMMA-RAY SOURCES AND THE SEARCH FOR TRANSIENTS IN OUR GALAXY2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 771, no 1, 57- p.Article in journal (Refereed)
    Abstract [en]

    In this paper, we present the Fermi All-sky Variability Analysis (FAVA), a tool to systematically study the variability of the gamma-ray sky measured by the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. For each direction on the sky, FAVA compares the number of gamma-rays observed in a given time window to the number of gamma-rays expected for the average emission detected from that direction. This method is used in weekly time intervals to derive a list of 215 flaring gamma-ray sources. We proceed to discuss the 27 sources found at Galactic latitudes smaller than 10 degrees and show that, despite their low latitudes, most of them are likely of extragalactic origin.

  • 9. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Allafort, A.
    Atwood, W. B.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bogart, J. R.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Bouvier, A.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Celik, O.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics.
    Corbet, R.
    Cutini, S.
    D'Ammando, F.
    Davis, D. S.
    de Angelis, A.
    DeKlotz, M.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fortin, P.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Giebels, B.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Jackson, M. S.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, R. P.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lavalley, C.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Nemmen, R.
    Nishino, S.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Racusin, J. L.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Reyes, L. C.
    Ritz, S.
    Rochester, L. S.
    Romoli, C.
    Roth, M.
    Sadrozinski, H. F. -W
    Sanchez, D. A.
    Parkinson, P. M. Saz
    Sbarra, C.
    Scargle, J. D.
    Sgro, C.
    Siegal-Gaskins, J.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Stephens, T. E.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Van Klaveren, B.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Wallace, E.
    Winer, B. L.
    Wood, D. L.
    Wood, K. S.
    Wood, M.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    THE FERMI LARGE AREA TELESCOPE ON ORBIT: EVENT CLASSIFICATION, INSTRUMENT RESPONSE FUNCTIONS, AND CALIBRATION2012In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 203, no 1, 4- p.Article in journal (Refereed)
    Abstract [en]

    The Fermi Large Area Telescope (Fermi-LAT, hereafter LAT), the primary instrument on the Fermi Gamma-ray Space Telescope (Fermi) mission, is an imaging, wide field-of-view, high-energy gamma-ray telescope, covering the energy range from 20 MeV to more than 300 GeV. During the first years of the mission, the LAT team has gained considerable insight into the in-flight performance of the instrument. Accordingly, we have updated the analysis used to reduce LAT data for public release as well as the instrument response functions (IRFs), the description of the instrument performance provided for data analysis. In this paper, we describe the effects that motivated these updates. Furthermore, we discuss how we originally derived IRFs from Monte Carlo simulations and later corrected those IRFs for discrepancies observed between flight and simulated data. We also give details of the validations performed using flight data and quantify the residual uncertainties in the IRFs. Finally, we describe techniques the LAT team has developed to propagate those uncertainties into estimates of the systematic errors on common measurements such as fluxes and spectra of astrophysical sources.

  • 10. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Allafort, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bloom, E. D.
    Bonamente, E.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cavazzuti, E.
    Chaves, R. C. G.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Franckowiak, A.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashida, M.
    Hewitt, J.
    Hughes, R. E.
    Jeltema, T. E.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Garde, Maja Llena
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ruan, J.
    Sanchez-Conde, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Storm, E.
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vianello, G.
    Vitale, V.
    Winer, B. L.
    Wood, K. S.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Pinzke, A.
    Pfrommer, C.
    SEARCH FOR COSMIC-RAY-INDUCED GAMMA-RAY EMISSION IN GALAXY CLUSTERS2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 787, no 1, 18Article in journal (Refereed)
    Abstract [en]

    Current theories predict relativistic hadronic particle populations in clusters of galaxies in addition to the already observed relativistic leptons. In these scenarios hadronic interactions give rise to neutral pions which decay into gamma rays that are potentially observable with the Large Area Telescope (LAT) on board the Fermi space telescope. We present a joint likelihood analysis searching for spatially extended gamma-ray emission at the locations of 50 galaxy clusters in four years of Fermi-LAT data under the assumption of the universal cosmic-ray (CR) model proposed by Pinzke & Pfrommer. We find an excess at a significance of 2.7 sigma, which upon closer inspection, however, is correlated to individual excess emission toward three galaxy clusters: A400, A1367, and A3112. We discuss these cases in detail and conservatively attribute the emission to unmodeled background systems (for example, radio galaxies within the clusters). Through the combined analysis of 50 clusters, we exclude hadronic injection efficiencies in simple hadronic models above 21% and establish limits on the CR to thermal pressure ratio within the virial radius, R-200, to be below 1.25%-1.4% depending on the morphological classification. In addition, we derive new limits on the gamma-ray flux from individual clusters in our sample.

  • 11. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Allafort, A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Bonamente, E.
    Bottacini, E.
    Bouvier, A.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chen, Q.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Inoue, Y.
    Jackson, M. S.
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jogler, T.
    Johannesson, G.
    Johnson, W. N.
    Kamae, T.
    Kawano, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Moretti, E.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Murphy, R.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Takahashi, H.
    Takeuchi, Y.
    Tanaka, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Tronconi, V.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, D. L.
    Wood, K. S.
    Wood, M.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    HIGH-ENERGY GAMMA-RAY EMISSION FROM SOLAR FLARES: SUMMARY OF FERMI LARGE AREA TELESCOPE DETECTIONS AND ANALYSIS OF TWO M-CLASS FLARES2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 787, no 1, 15- p.Article in journal (Refereed)
    Abstract [en]

    We present the detections of 18 solar flares detected in high-energy gamma-rays (above 100 MeV) with the Fermi Large Area Telescope (LAT) during its first 4 yr of operation. This work suggests that particle acceleration up to very high energies in solar flares is more common than previously thought, occurring even in modest flares, and for longer durations. Interestingly, all these flares are associated with fairly fast coronal mass ejections (CMEs). We then describe the detailed temporal, spatial, and spectral characteristics of the first two long-lasting events: the 2011 March 7 flare, a moderate (M3.7) impulsive flare followed by slowly varying gamma-ray emission over 13 hr, and the 2011 June 7 M2.5 flare, which was followed by gamma-ray emission lasting for 2 hr. We compare the Fermi LAT data with X-ray and proton data measurements from GOES and RHESSI. We argue that the gamma-rays are more likely produced through pion decay than electron bremsstrahlung, and we find that the energy spectrum of the proton distribution softens during the extended emission of the 2011 March 7 flare. This would disfavor a trapping scenario for particles accelerated during the impulsive phase of the flare and point to a continuous acceleration process at play for the duration of the flares. CME shocks are known for accelerating the solar energetic particles (SEPs) observed in situ on similar timescales, but it might be challenging to explain the production of gamma-rays at the surface of the Sun while the CME is halfway to the Earth. A stochastic turbulence acceleration process occurring in the solar corona is another likely scenario. Detailed comparison of characteristics of SEPs and gamma-ray-emitting particles for several flares will be helpful to distinguish between these two possibilities.

  • 12. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Allafort, A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Bottacini, E.
    Bouvier, A.
    Brandt, T. J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    Dalton, M.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Di Venere, L.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hayashi, K.
    Hewitt, J. W.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    Jackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kawano, T.
    Knödlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Roth, M.
    Schaal, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Takahashi, H.
    Takeuchi, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Tronconi, V.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Yang, Z.
    Inferred Cosmic-Ray Spectrum from Fermi Large Area Telescope gamma-Ray Observations of Earth's Limb2014In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 112, no 15, 151103- p.Article in journal (Refereed)
    Abstract [en]

    Recent accurate measurements of cosmic-ray (CR) species by ATIC-2, CREAM, and PAMELA reveal an unexpected hardening in the proton and He spectra above a few hundred GeV, a gradual softening of the spectra just below a few hundred GeV, and a harder spectrum of He compared to that of protons. These newly discovered features may offer a clue to the origin of high-energy CRs. We use the Fermi Large Area Telescope observations of the gamma-ray emission from Earth's limb for an indirect measurement of the local spectrum of CR protons in the energy range similar to 90 GeV-6 TeV (derived from a photon energy range 15 GeV-1 TeV). Our analysis shows that single power law and broken power law spectra fit the data equally well and yield a proton spectrum with index 2.68 +/- 0.04 and 2.61 +/- 0.08 above similar to 200 GeV, respectively.

  • 13. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Anderson, Brandon
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Arimoto, M.
    Atwood, W. B.
    Axelsson, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Gonzalez, J. Becerra
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Britto, R. J.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Condon, B.
    Costanza, F.
    Cuoco, A.
    Cutini, S.
    D'Ammando, F.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Lalla, N.
    Di Mauro, M.
    Di Venere, L.
    Dominguez, A.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Giglietto, N.
    Giomi, M.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Granot, J.
    Green, D.
    Grenier, I. A.
    Grondin, M. -H.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Jogler, T.
    Johannesson, G.
    Kamae, T.
    Kensei, S.
    Kocevski, D.
    Kuss, M.
    La Mura, G.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Li, J.
    Li, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Magill, J.
    Maldera, S.
    Manfreda, A.
    Marelli, M.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Meyer, Manuel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Michelson, P. F.
    Mirabal, N.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Moretti, E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Negro, M.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Racusin, J. L.
    Raino, S.
    Rando, R.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Rochester, L. S.
    Romani, R. W.
    Parkinson, P. M. Saz
    Sgro, C.
    Simone, D.
    Siskind, E. J.
    Smith, D. A.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Venters, T. M.
    Vianello, G.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Zhu, S.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    FERMI-LAT OBSERVATIONS OF THE LIGO EVENT GW1509142016In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 823, no 1, L2Article in journal (Refereed)
    Abstract [en]

    The Fermi Large Area Telescope (LAT) has an instantaneous field of view (FoV) covering similar to 1/5 of the sky and it completes a survey of the entire sky in high-energy gamma-rays every 3 hr. It enables searches for transient phenomena over timescales from milliseconds to years. Among these phenomena could be electromagnetic counterparts to gravitational wave (GW) sources. In this paper, we present a detailed study of the LAT observations relevant to Laser Interferometer Gravitational-wave Observatory (LIGO) event GW150914, which is the first direct detection of gravitational waves and has been interpreted as being due to the coalescence of two stellar-mass black holes. The localization region for GW150914 was outside the LAT FoV at the time of the GW signal. However, as part of routine survey observations, the LAT observed the entire LIGO localization region within similar to 70 minutes of the trigger and thus enabled a comprehensive search for a.-ray counterpart to GW150914. The study of the LAT data presented here did not find any potential counterparts to GW150914, but it did provide limits on the presence of a transient counterpart above 100 MeV on timescales of hours to days over the entire GW150914 localization region.

  • 14. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Anderson, Brandon
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Atwood, W. B.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cuoco, A.
    AlbaNova, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Gustafsson, M.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Johannesson, G.
    Johnson, R. P.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Li, J.
    Li, L.
    AlbaNova, Oskar Klein Ctr Cosmoparticle Phys, SE-10691 Stockholm, Sweden.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Malyshev, D.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Murgia, S.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reposeur, T.
    Ritz, S.
    Sanchez-Coude, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Tajima, H.
    Takahashi, H.
    Thayer, J. B.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Vianello, G.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Updated search for spectral lines from Galactic dark matter interactions with pass 8 data from the Fermi Large Area Telescope2015In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 91, no 12Article in journal (Refereed)
    Abstract [en]

    Dark matter in the Milky Way may annihilate directly into. rays, producing a monoenergetic spectral line. Therefore, detecting such a signature would be strong evidence for dark matter annihilation or decay. We search for spectral lines in the Fermi Large Area Telescope observations of the Milky Way halo in the energy range 200 MeV-500 GeV using analysis methods from our most recent line searches. The main improvements relative to previous works are our use of 5.8 years of data reprocessed with the Pass 8 event-level analysis and the additional data resulting from the modified observing strategy designed to increase exposure of the Galactic center region. We search in five sky regions selected to optimize sensitivity to different theoretically motivated dark matter scenarios and find no significant detections. In addition to presenting the results from our search for lines, we also investigate the previously reported tentative detection of a line at 133 GeV using the new Pass 8 data.

  • 15. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Becerra Gonzalez, J.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Di Venere, L.
    Dominguez, A.
    Drell, P. S.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fuhrmann, L.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Green, D.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Harding, A. K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Li, J.
    Li, Lang
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Magill, J.
    Maldera, S.
    Manfreda, A.
    Max-Moerbeck, W.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Ojha, R.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Pearson, T. J.
    Perkins, J. S.
    Perri, M.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Readhead, A.
    Reimer, A.
    Reimer, O.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Takahashi, H.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Wood, K. S.
    Wood, M.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Berdyugin, A.
    Corbet, R. H. D.
    Hovatta, T.
    Lindfors, E.
    Nilsson, K.
    Reinthal, R.
    Sillanpaa, A.
    Stamerra, A.
    Takalo, L. O.
    Valtonen, M. J.
    MULTIWAVELENGTH EVIDENCE FOR QUASI-PERIODIC MODULATION IN THE GAMMA-RAY BLAZAR PG 1553+1132015In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 813, no 2, L41Article in journal (Refereed)
    Abstract [en]

    We report for the first time a gamma-ray and multiwavelength nearly periodic oscillation in an active galactic nucleus. Using the Fermi Large Area Telescope we have discovered an apparent quasi-periodicity in the gamma-ray flux (E > 100 MeV) from the GeV/TeV BL Lac object PG 1553+113. The marginal significance of the 2.18 +/- 0.08 year period gamma-ray cycle is strengthened by correlated oscillations observed in radio and optical fluxes, through data collected in the Owens Valley Radio Observatory, Tuorla, Katzman Automatic Imaging Telescope, and Catalina Sky Survey monitoring programs and Swift-UVOT. The optical cycle appearing in similar to 10 years of data has a similar period, while the 15 GHz oscillation is less regular than seen in the other bands. Further long-term multiwavelength monitoring of this blazar may discriminate among the possible explanations for this quasi-periodicity.

  • 16. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Sciences, Sweden.
    Cuoco, A.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Favuzzi, C.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashi, K.
    Hays, E.
    Hewitt, J. W.
    Ippoliti, P.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Li, J.
    EGENLi, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Manfreda, A.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Romani, R. W.
    Sanchez-Conde, M.
    Schaal, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    THE SPECTRUM OF ISOTROPIC DIFFUSE GAMMA-RAY EMISSION BETWEEN 100 MeV AND 820 GeV2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 799, no 1, 86- p.Article in journal (Refereed)
    Abstract [en]

    The gamma-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse gamma-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission (DGE), and a longer data accumulation of 50 months allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 +/- 0.02 and a break energy of (279 +/- 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is (7.2 +/- 0.6) x 10(-6) cm(-2) s(-1) sr(-1) above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.

  • 17. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon,
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiappo, Andrea
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Chiaro, G.
    Ciprini, S.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Costanza, F.
    Cuoco, A.
    Cutini, S.
    D'Ammando, F.
    de Palmai, F.
    Desiante, R.
    Digel, S. W.
    Di Lalla, N.
    Di Mauro, M.
    Di Venere, L.
    Drell, P. S.
    Favuzzi, C.
    Fegan, J.
    Ferrara, E. C.
    Fockes, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gaspanini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Gomez-Vargas, G. A.
    Green, D.
    Grenier, I. A.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Gustafsson, M.
    Harding, A. K.
    Hays, E.
    Hewitt, J. W.
    Horan, D.
    Jogler, T.
    Johnson, A. S.
    Kamae, T.
    Kocevski, D.
    Kuss, M.
    La Mura, G.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). KTH Royal Institute of Technology, Sweden.
    Latronico, L.
    Li, J.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Magill, J. D.
    Maldera, S.
    Malyshev, D.
    Manfreda, A.
    Martin, P.
    Mazziottam, M. N.
    Michelson, P. F.
    Mirabal, N.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Negro, M.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Persic, M.
    Pesce-Rollins, M.
    Piron, F.
    Principe, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Sanchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Sgro, C.
    Simone, D.
    Siskind, E. J.
    Spada, F.
    Spandrel, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Tanaka, K.
    Thayer, J. B.
    Tibaldo, L.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Zimmer, S.
    The Fermi Galactic Center GeV Excess and Implications for Dark Matter2017In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 840, no 1, 43Article in journal (Refereed)
    Abstract [en]

    The region around the Galactic Center (GC) is now well established to be brighter at energies of a few GeV than what is expected from conventional models of diffuse gamma-ray emission and catalogs of known gamma-ray sources. We study the GeV excess using 6.5 yr of data from the Fermi Large Area Telescope. We characterize the uncertainty of the GC excess spectrum and morphology due to uncertainties in cosmic-ray source distributions and propagation, uncertainties in the distribution of interstellar gas in the Milky Way, and uncertainties due to a potential contribution from the Fermi bubbles. We also evaluate uncertainties in the excess properties due to resolved point sources of gamma rays. The GC is of particular interest, as it would be expected to have the brightest signal from annihilation of weakly interacting massive dark matter (DM) particles. However, control regions along the Galactic plane, where a DM signal is not expected, show excesses of similar amplitude relative to the local background. Based on the magnitude of the systematic uncertainties, we conservatively report upper limits for the annihilation cross-section as a function of particle mass and annihilation channel.

  • 18. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Sciences, Sweden.
    Corbel, S.
    D'Ammando, F.
    de Angelis, A.
    den Hartog, P. R.
    de Palma, F.
    Dermer, C. D.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    do Couto e Silva, E.
    Donato, D.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Fuhrmann, L.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Hou, X.
    Jean, P.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Sciences, Sweden.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Manfreda, A.
    Martin, P.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Parkinson, P. M. Saz
    Schaal, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Stawarz, L.
    Suson, D. J.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Winer, B. L.
    Wolff, M. T.
    Wood, D. L.
    Wood, K. S.
    Wood, M.
    Charbonnel, S.
    Corbet, R. H. D.
    Aquino, I. De Gennaro
    Edlin, J. P.
    Mason, E.
    Schwarz, G. J.
    Shore, S. N.
    Starrfield, S.
    Teyssier, F.
    Fermi establishes classical novae as a distinct class of gamma-ray sources2014In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 345, no 6196, 554-558 p.Article in journal (Refereed)
    Abstract [en]

    A classical nova results from runaway thermonuclear explosions on the surface of a white dwarf that accretes matter from a low-mass main-sequence stellar companion. In 2012 and 2013, three novae were detected in gamma rays and stood in contrast to the first gamma-ray-detected nova V407 Cygni 2010, which belongs to a rare class of symbiotic binary systems. Despite likely differences in the compositions and masses of their white dwarf progenitors, the three classical novae are similarly characterized as soft-spectrum transient gamma-ray sources detected over 2- to 3-week durations. The gamma-ray detections point to unexpected high-energy particle acceleration processes linked to the mass ejection from thermonuclear explosions in an unanticipated class of Galactic gamma-ray sources.

  • 19. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Bloom, E. D.
    Bonino, R.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cuoco, Alessandro
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Istituto Nazionale di Fisica Nucleare, Sezione di Torino, Italy; Universita degli Studi di Torino, Italy.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Ferrara, E. C.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Guiriec, S.
    Gustafsson, M.
    Hewitt, J. W.
    Hou, X.
    Kamae, T.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Malyshev, D.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Negro, M.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Sánchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Zaharijas, G.
    Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background2015In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 9, 008Article in journal (Refereed)
    Abstract [en]

    We search for evidence of dark matter (DM) annihilation in the isotropic gamma-ray background (IGRB) measured with 50 months of Fermi Large Area Telescope (LAT) observations. An improved theoretical description of the cosmological DM annihilation signal, based on two complementary techniques and assuming generic weakly interacting massive particle (WIMP) properties, renders more precise predictions compared to previous work. More specifically, we estimate the cosmologically-induced gamma-ray intensity to have an uncertainty of a factor similar to 20 in canonical setups. We consistently include both the Galactic and extragalactic signals under the same theoretical framework, and study the impact of the former on the IGRB spectrum derivation. We find no evidence for a DM signal and we set limits on the DM-induced isotropic gamma-ray signal. Our limits are competitive for DM particle masses up to tens of TeV and, indeed, are the strongest limits derived from Fermi LAT data at TeV energies. This is possible thanks to the new Fermi LAT IGRB measurement, which now extends up to an energy of 820 GeV. We quantify uncertainties in detail and show the potential this type of search offers for testing the WIMP paradigm with a complementary and truly cosmological probe of DM particle signals.

  • 20. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Antolini, E.
    Atwood, W. B.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Bouvier, A.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Costamante, L.
    Cutini, S.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Silva, E. do Couto e.
    Drell, P. S.
    Dubois, R.
    Escande, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Healey, S. E.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Iafrate, G.
    Jóhannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knödlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Moretti, E.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Naumann-Godo, M.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Parent, D.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piranomonte, S.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Rainò, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Rochester, L. S.
    Romani, R. W.
    Roth, M.
    Sanchez, D. A.
    Sbarra, C.
    Scargle, J. D.
    Schalk, T. L.
    Sgrò, C.
    Shaw, M. S.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Wallace, E.
    Wang, P.
    Winer, B. L.
    Wood, D. L.
    Wood, K. S.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics.
    The Second Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 743, no 2, 171- p.Article in journal (Refereed)
    Abstract [en]

    The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The second LAT AGN catalog (2LAC) includes 1017 γ-ray sources located at high Galactic latitudes (|b| > 10°) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However, some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently, we define a Clean Sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broadband blazar characteristics but with no optical spectral measurement yet), 8 misaligned AGNs, 4 narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types, and 2 starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency <1014 Hz, about half of the BL Lac objects have a synchrotron-peak frequency >1015 Hz. The 2LAC represents a significant improvement relative to the first LAT AGN catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broadband data. Various properties, such as γ-ray fluxes and photon power-law spectral indices, redshifts, γ-ray luminosities, variability, and archival radio luminosities and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.

  • 21. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Antolini, E.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Chekhtman, A.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Enoto, T.
    Falletti, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fukazawa, Y.
    Fukui, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hayashi, K.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Jackson, M. S.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knodlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy.
    Lee, S. -H
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Makishima, K.
    Mazziotta, M. N.
    Mehault, J.
    Mitthumsiri, W.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Naumann-Godo, M.
    Nishino, S.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Roth, M.
    Sadrozinski, H. F. -W
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Tibolla, O.
    Tinivella, M.
    Torres, D. F.
    Tramacere, A.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Gamma ray observations of the orion molecular clouds with the fermi large area telescope2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 756, no 1, 4- p.Article in journal (Refereed)
    Abstract [en]

    We report on the gamma-ray observations of giant molecular clouds Orion A and B with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. The gamma-ray emission in the energy band between similar to 100 MeV and similar to 100 GeV is predicted to trace the gas mass distribution in the clouds through nuclear interactions between the Galactic cosmic rays (CRs) and interstellar gas. The gamma-ray production cross-section for the nuclear interaction is known to similar to 10% precision which makes the LAT a powerful tool to measure the gas mass column density distribution of molecular clouds for a known CR intensity. We present here such distributions for Orion A and B, and correlate them with those of the velocity-integrated CO intensity (W-CO) at a 1 degrees x 1 degrees pixel level. The correlation is found to be linear over a W-CO range of similar to 10-fold when divided in three regions, suggesting penetration of nuclear CRs to most of the cloud volumes. The W-CO-to-mass conversion factor, X-CO, is found to be similar to 2.3 x 10(20) cm(-2) (K km s(-1))(-1) for the high-longitude part of Orion A (l > 212 degrees), similar to 1.7 times higher than similar to 1.3 x 10(20) found for the rest of Orion A and B. We interpret the apparent high XCO in the high-longitude region of Orion A in the light of recent works proposing a nonlinear relation between H-2 and CO densities in the diffuse molecular gas. W-CO decreases faster than the H-2 column density in the region making the gas darker to W-CO.

  • 22. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Asano, K.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Busetto, G.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chaty, S.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Cillis, A. N.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Colafrancesco, S.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    D'Ammando, F.
    de Palma, F.
    Dermer, C. D.
    do Couto e Silva, E.
    Drell, S.
    Drlica-Wagner, A.
    Dubois, R.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fortin, P.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grandi, P.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Jackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, R. P.
    Johnson, A. S.
    Kamae, T.
    Kataoka, J.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Latronico, L.
    Lavalley, C.
    Lee, S. -H
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mignani, R. P.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Nemmen, R.
    Nishino, S.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Pelassa, V.
    Perkins, J. S.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Poon, H.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reyes, L. C.
    Ritz, S.
    Rochester, L. S.
    Romoli, C.
    Roth, M.
    Sanchez, D. A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Snyder, A.
    Spandre, G.
    Spinelli, P.
    Stephens, T. E.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    von Kienlin, A.
    Waite, A. P.
    Wallace, E.
    Weltevrede, P.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    DETERMINATION OF THE POINT-SPREAD FUNCTION FOR THE FERMI LARGE AREA TELESCOPE FROM ON-ORBIT DATA AND LIMITS ON PAIR HALOS OF ACTIVE GALACTIC NUCLEI2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 765, no 1, 54- p.Article in journal (Refereed)
    Abstract [en]

    The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope is a pair-conversion telescope designed to detect photons with energies from approximate to 20 MeV to > 300 GeV. The pre-launch response functions of the LAT were determined through extensive Monte Carlo simulations and beam tests. The point-spread function (PSF) characterizing the angular distribution of reconstructed photons as a function of energy and geometry in the detector is determined here from two years of on-orbit data by examining the distributions of gamma rays from pulsars and active galactic nuclei (AGNs). Above 3 GeV, the PSF is found to be broader than the pre-launch PSF. We checked for dependence of the PSF on the class of gamma-ray source and observation epoch and found none. We also investigated several possible spatial models for pair-halo emission around BL Lac AGNs. We found no evidence for a component with spatial extension larger than the PSF and set upper limits on the amplitude of halo emission in stacked images of low-and high-redshift BL Lac AGNs and the TeV blazars 1ES0229 + 200 and 1ES0347-121.

  • 23. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Belfiore, A.
    Bellazzini, R.
    Bernieri, E.
    Bissaldi, E.
    Bloom, E. D.
    Bonamente, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Campana, R.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences.
    Cutini, S.
    D'Ammando, F.
    De Angelis, A.
    De Palma, F.
    Dermer, C. D.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fortin, P.
    Franckowiak, A.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Gomez-Vargas, G. A.
    Grenier, I. A.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hewitt, J.
    Hill, A. B.
    Horan, D.
    Hughes, R. E.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Kawano, T.
    Knodlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Massaro, E.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Orienti, M.
    Ormes, J. F.
    Paneque, David
    Stockholm University, Faculty of Science, Department of Astronomy. Max Planck Institute for Physics and Astrophysics, Germany.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Romani, R. W.
    Roth, M.
    Parkinson, P. M. Saz
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Spandre, G.
    Spinelli, P.
    Stawarz, Lukasz
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    THE FIRST FERMI-LAT CATALOG OF SOURCES ABOVE 10 GeV2013In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 209, no 2Article in journal (Refereed)
    Abstract [en]

    We present a catalog of gamma-ray sources at energies above 10 GeV based on data from the Large Area Telescope (LAT) accumulated during the first 3 yr of the Fermi Gamma-ray Space Telescope mission. The first Fermi catalog of > 10 GeV sources (1FHL) has 514 sources. For each source we present location, spectrum, a measure of variability, and associations with cataloged sources at other wavelengths. We found that 449 (87%) could be associated with known sources, of which 393 (76% of the 1FHL sources) are active galactic nuclei. Of the 27 sources associated with known pulsars, we find 20 (12) to have significant pulsations in the range > 10 GeV (> 25 GeV). In this work we also report that, at energies above 10 GeV, unresolved sources account for 27% +/- 8% of the isotropic. gamma-ray background, while the unresolved Galactic population contributes only at the few percent level to the Galactic diffuse background. We also highlight the subset of the 1FHL sources that are best candidates for detection at energies above 50-100 GeV with current and future ground-based gamma-ray observatories.

  • 24. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Busetto, G.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Celik, O.
    Charles, E.
    Chaty, S.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Cillis, A. N.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Corbel, S.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Falletti, L.
    Favuzzi, C.
    Ferrara, E. C.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hayashi, K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Hughes, R. E.
    Jackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kataoka, J.
    Katsuta, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mignani, R. P.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Romoli, C.
    Sanchez-Conde, M.
    Schulz, A.
    Sgro, C.
    Simeon, P. E.
    Siskind, E. J.
    Smith, D. A.
    Spandre, G.
    Spinelli, P.
    Stecker, F. W.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Thorsett, S. E.
    Tibaldo, L.
    Tibolla, O.
    Tinivella, M.
    Troja, E.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Yamazaki, R.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Detection of the Characteristic Pion-Decay Signature in Supernova Remnants2013In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 339, no 6121, 807-811 p.Article in journal (Refereed)
    Abstract [en]

    Cosmic rays are particles (mostly protons) accelerated to relativistic speeds. Despite wide agreement that supernova remnants (SNRs) are the sources of galactic cosmic rays, unequivocal evidence for the acceleration of protons in these objects is still lacking. When accelerated protons encounter interstellar material, they produce neutral pions, which in turn decay into gamma rays. This offers a compelling way to detect the acceleration sites of protons. The identification of pion-decay gamma rays has been difficult because high-energy electrons also produce gamma rays via bremsstrahlung and inverse Compton scattering. We detected the characteristic pion-decay feature in the gamma-ray spectra of two SNRs, IC 443 and W44, with the Fermi Large Area Telescope. This detection provides direct evidence that cosmic-ray protons are accelerated in SNRs.

  • 25. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Busetto, G.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Falletti, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fukazawa, Y.
    Fukui, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashi, K.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Itoh, R.
    Jackson, M. S.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Lee, S. -H
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Martin, P.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Nemmen, R.
    Nishino, S.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Romoli, C.
    Roth, M.
    Sada, T.
    Sadrozinski, H. F. -W
    Sanchez, D. A.
    Sbarra, C.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strong, A. W.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Troja, E.
    Uchiyama, Y.
    Uehara, T.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yamamoto, H.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    FERMI LARGE AREA TELESCOPE STUDY OF COSMIC RAYS AND THE INTERSTELLAR MEDIUM IN NEARBY MOLECULAR CLOUDS2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 755, no 1, 22- p.Article in journal (Refereed)
    Abstract [en]

    We report an analysis of the interstellar gamma-ray emission from the Chamaeleon, R Coronae Australis (R CrA), and Cepheus and Polaris flare regions with the Fermi Large Area Telescope. They are among the nearest molecular cloud complexes, within similar to 300 pc from the solar system. The gamma-ray emission produced by interactions of cosmic rays (CRs) and interstellar gas in those molecular clouds is useful to study the CR densities and distributions of molecular gas close to the solar system. The obtained gamma-ray emissivities above 250 MeV are (5.9 +/- 0.1(stat-1.0sys)(+0.9)) x 10(-27) photons s(-1) sr(-1) H-atom(-1), (10.2 +/- 0.4(stat-1.7sys)(+1.2)) x 10(-27) photons s(-1) sr(-1) H-atom(-1), and (9.1 +/- 0.3(stat-0.6sys)(+1.5)) x 10(-27) photons s(-1) sr(-1) H-atom(-1) for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively. Whereas the energy dependences of the emissivities agree well with that predicted from direct CR observations at the Earth, the measured emissivities from 250 MeV to 10 GeV indicate a variation of the CR density by similar to 20% in the neighborhood of the solar system, even if we consider systematic uncertainties. The molecular mass calibrating ratio, X-CO = N(H-2)/W-CO, is found to be (0.96 +/- 0.06(stat-0.12sys)(+0.15)) x 10(20) H-2-molecule cm(-2) (K km s(-1))(-1), (0.99 +/- 0.08(stat-0.10sys)(+0.18)) x 10(20) H-2-molecule cm(-2) (K km s(-1))(-1), and (0.63 +/- 0.02(stat-0.07sys)(+0.09)) x 10(20) H-2-molecule cm(-2) (K km s(-1))(-1) for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively, suggesting a variation of X-CO in the vicinity of the solar system. From the obtained values of X-CO, the masses of molecular gas traced by W-CO in the Chamaeleon, R CrA, and Cepheus and Polaris flare regions are estimated to be similar to 5 x 10(3)M(circle dot), similar to 10(3)M(circle dot), and similar to 3.3 x 10(4)M(circle dot), respectively. A comparable amount of gas not traced well by standard Hi and CO surveys is found in the regions investigated.

  • 26. Ackermann, M.
    et al.
    Ajello, M.
    Allafort, A.
    Schady, P.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Blandford, R. D.
    Bloom, E. D.
    Borgland, A. W.
    Bottacini, E.
    Bouvier, A.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    D'Ammando, F.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    do Couto e Silva, E.
    Domnguez, A.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Jackson, M. S.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Jogler, T.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Tramacere, A.
    Nuss, E.
    Greiner, J.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reyes, L. C.
    Ritz, S.
    Rau, A.
    Romoli, C.
    Roth, M.
    Sanchez-Conde, M.
    Sanchez, D. A.
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Stawarz, Lukasz
    Suson, D. J.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    The Imprint of the Extragalactic Background Light in the Gamma-Ray Spectra of Blazars2012In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 338, no 6111, 1190-1192 p.Article in journal (Refereed)
    Abstract [en]

    The light emitted by stars and accreting compact objects through the history of the universe is encoded in the intensity of the extragalactic background light (EBL). Knowledge of the EBL is important to understand the nature of star formation and galaxy evolution, but direct measurements of the EBL are limited by galactic and other foreground emissions. Here, we report an absorption feature seen in the combined spectra of a sample of gamma-ray blazars out to a redshift of z similar to 1.6. This feature is caused by attenuation of gamma rays by the EBL at optical to ultraviolet frequencies and allowed us to measure the EBL flux density in this frequency band.

  • 27. Ackermann, M.
    et al.
    Ajello, M.
    An, H.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bonino, R.
    Bregeon, J.
    Britto, R. J.
    Bruel, P.
    Buehler, R.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiaro, G.
    Ciprini, S.
    Cohen-Tanugi, J.
    Costanza, F.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Di Mauro, M.
    Di Venere, L.
    Dominiguez, A.
    Drell, P. S.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Green, D.
    Grenier, I. A.
    Guiriec, S.
    Horan, D.
    Johannesson, G.
    Katsuragawa, M.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Li, J.
    Li, Lang
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Magill, J.
    Maldera, S.
    Manfreda, A.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mirabal, N.
    Mitthumsiri, W.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Negro, M.
    Nuss, E.
    Ohsugi, T.
    Okada, C.
    Orlando, E.
    Paneque, D.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, O.
    Rau, A.
    Romani, R. W.
    Schady, P.
    Sgro, C.
    Simone, D.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Stern, D.
    Takahashi, H.
    Thayer, J. B.
    Torres, D. F.
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Tosti, G.
    Troja, E.
    Vianello, G.
    Wood, K. S.
    Wood, M.
    CONTEMPORANEOUS BROADBAND OBSERVATIONS OF THREE HIGH-REDSHIFT BL LAC OBJECTS2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 820, no 1, 72Article in journal (Refereed)
    Abstract [en]

    We have collected broadband spectral energy distributions (SEDs) of three BL Lac objects 3FGL J0022.1-1855 (z = 0.689), 3FGL J0630.9-2406 (z greater than or similar to 1.239), and 3FGL J0811.2-7529 (z = 0.774), detected by Fermi with relatively flat gigaelectronvolt spectra. By observing simultaneously in the near-infrared to hard X-ray band, we can well characterize the high end of the synchrotron component of the SED. Thus, fitting the SEDs to synchro-Compton models of the dominant emission from the relativistic jet, we can constrain the underlying particle properties and predict the shape of the gigaelectronvolt Compton component. Standard extragalactic background light (EBL) models explain the high-energy absorption well, with poorer fits for high-ultraviolet models. The fits show clear evidence for EBL absorption in the Fermi spectrum of our highest-redshift source 3FGL J0630.9-2406. While synchrotron self-Compton models adequately describe the SEDs, the situation may be complicated by possible external Compton components. For 3FGL J0811.2-7529, we also discover a nearby serendipitous source in the X-ray data, which is almost certainly another lower synchrotron peak frequency (nu(sy)(pk)) BL Lac, that may contribute flux in the Fermi band. Since our sources are unusual high-luminosity, moderate nu(sy)(pk) BL Lacs, we compare these quantities and the Compton dominance, the ratio of peak inverse Compton to peak synchrotron luminosities (L-pk(IC)/L-pk(sy)), with those of the full Fermi BL Lac population.

  • 28. Ackermann, M.
    et al.
    Ajello, M.
    Anderson, B.
    Atwood, W. B.
    Axelsson, M.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bhat, P. N.
    Bissaldi, E.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Di Venere, L.
    Drell, P. S.
    Favuzzi, C.
    Focke, W. B.
    Franckowiak, A.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Johannesson, G.
    Kocevski, D.
    Kouveliotou, C.
    Kuss, M.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Li, J.
    Li, Liang
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). KTH Royal Institute of Technology, Sweden.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Racusin, J. L.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Schaal, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Takahashi, H.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Vianello, G.
    von Kienlin, A.
    Werner, M.
    Wood, K. S.
    FERMI LAT STACKING ANALYSIS OF SWIFT LOCALIZED GRBs2016In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 822, no 2, 68Article in journal (Refereed)
    Abstract [en]

    We perform a comprehensive stacking analysis of data collected by the Fermi. Large Area Telescope (LAT) of gamma-ray bursts (GRBs) localized by the Swift. spacecraft, which were not detected by the LAT but which fell within the instrument's field of view at the time of trigger. We examine a total of 79 GRBs by comparing the observed counts over a range of time intervals to that expected from designated background orbits, as well as by using a joint likelihood technique to model the expected distribution of stacked counts. We find strong evidence for subthreshold emission at MeV to GeV energies using both techniques. This observed excess is detected during intervals that include and exceed the durations typically characterizing the prompt emission observed at keV energies and lasts at least 2700 s after the co-aligned burst trigger. By utilizing a novel cumulative likelihood analysis, we find that although a burst's prompt gamma-ray and afterglow X-ray flux both correlate with the strength of the subthreshold emission, the X-ray afterglow flux measured by Swift's X-ray Telescope at 11 hr post trigger correlates far more significantly. Overall, the extended nature of the subthreshold emission and its connection to the burst's afterglow brightness lend. further support to the external forward shock origin of the late-time emission detected by the LAT. These results suggest that the extended high-energy emission observed by the LAT may be a relatively common feature but remains undetected in a majority of bursts owing. to instrumental threshold effects.

  • 29. Ackermann, M.
    et al.
    Ajello, M.
    Asano, K.
    Atwood, W. B.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bissaldi, E.
    Bonamente, E.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burgess, J. Michael
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Chaplin, V.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cleveland, W.
    Cohen-Tanugi, J.
    Collazzi, A.
    Cominsky, L. R.
    Connaughton, V.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    DeKlotz, M.
    de Palma, F.
    Dermer, C. D.
    Desiante, R.
    Diekmann, A.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Fitzpatrick, G.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gehrels, N.
    Germani, S.
    Gibby, M.
    Giglietto, N.
    Giles, M.
    Giordano, F.
    Giroletti, M.
    Godfrey, G.
    Granot, J.
    Grenier, I. A.
    Grove, J. E.
    Gruber, D.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Inoue, Y.
    Jogler, T.
    Johannesson, G.
    Johnson, W. N.
    Kawano, T.
    Knoedlseder, J.
    Kocevski, D.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Moretti, E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orienti, M.
    Paneque, D.
    Pelassa, V.
    Perkins, J. S.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Racusin, J. L.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Roth, M.
    Ryde, F.
    Sartori, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Sonbas, E.
    Spandre, G.
    Spinelli, P.
    Tajima, H.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Winer, B. L.
    Wood, K. S.
    Yamazaki, R.
    Younes, G.
    Yu, H. -F
    Zhu, S. J.
    Bhat, P. N.
    Briggs, M. S.
    Byrne, D.
    Foley, S.
    Goldstein, A.
    Jenke, P.
    Kippen, R. M.
    Kouveliotou, C.
    McBreen, S.
    Meegan, C.
    Paciesas, W. S.
    Preece, R.
    Rau, A.
    Tierney, D.
    van der Horst, A. J.
    von Kienlin, A.
    Wilson-Hodge, C.
    Xiong, S.
    Cusumano, G.
    La Parola, V.
    Cummings, J. R.
    Fermi-LAT Observations of the Gamma-Ray Burst GRB 130427A2014In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 343, no 6166, 42-47 p.Article in journal (Refereed)
    Abstract [en]

    The observations of the exceptionally bright gamma-ray burst (GRB) 130427A by the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope provide constraints on the nature of these unique astrophysical sources. GRB 130427A had the largest fluence, highest-energy photon (95 GeV), longest gamma-ray duration (20 hours), and one of the largest isotropic energy releases ever observed from a GRB. Temporal and spectral analyses of GRB 130427A challenge the widely accepted model that the nonthermal high-energy emission in the afterglow phase of GRBs is synchrotron emission radiated by electrons accelerated at an external shock.

  • 30. Ackermann, M.
    et al.
    Ajello, M.
    Asano, K.
    Axelsson, Magnus
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bhat, P. N.
    Bissaldi, E.
    Bloom, E. D.
    Bonamente, E.
    Bonnell, J.
    Bouvier, A.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burgess, J. Michael
    Buson, S.
    Byrne, D.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Connaughton, V.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Desiante, R.
    Digel, S. W.
    Dingus, B. L.
    Di Venere, L.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Favuzzi, C.
    Ferrara, E. C.
    Fitzpatrick, G.
    Foley, S.
    Franckowiak, A.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Goldstein, A.
    Granot, J.
    Grenier, I. A.
    Grove, J. E.
    Gruber, D.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Hayashida, M.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    Jackson, M. S.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Kawano, T.
    Kippen, R. M.
    Knoedlseder, J.
    Kocevski, D.
    Kouveliotou, C.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Lee, S. -H
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Massaro, F.
    Mayer, M.
    Mazziotta, M. N.
    McBreen, S.
    McEnery, J. E.
    McGlynn, S.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Moretti, E.
    Morselli, A.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Nymark, T.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Paciesas, W. S.
    Paneque, D.
    Panetta, J. H.
    Pelassa, V.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Preece, R.
    Racusin, J. L.
    Raino, S.
    Rando, R.
    Rau, A.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Romoli, C.
    Roth, M.
    Ryde, F.
    Parkinson, P. M. Saz
    Schalk, T. L.
    Sgro, C.
    Siskind, E. J.
    Sonbas, E.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takeuchi, Y.
    Tanaka, Y.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tierney, D.
    Tinivella, M.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Tronconi, V.
    Usher, T. L.
    Vandenbroucke, J.
    van der Horst, A. J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    von Kienlin, A.
    Winer, B. L.
    Wood, K. S.
    Wood, M.
    Xiong, S.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    THE FIRST FERMI-LAT GAMMA-RAY BURST CATALOG2013In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 209, no 1Article in journal (Refereed)
    Abstract [en]

    In three years of observations since the beginning of nominal science operations in 2008 August, the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope has observed high-energy (greater than or similar to 20 MeV) gamma-ray emission from 35 gamma-ray bursts (GRBs). Among these, 28 GRBs have been detected above 100 MeV and 7 GRBs above similar to 20 MeV. The first Fermi-LAT catalog of GRBs is a compilation of these detections and provides a systematic study of high-energy emission from GRBs for the first time. To generate the catalog, we examined 733 GRBs detected by the Gamma-Ray Burst Monitor (GBM) on Fermi and processed each of them using the same analysis sequence. Details of the methodology followed by the LAT collaboration for the GRB analysis are provided. We summarize the temporal and spectral properties of the LAT-detected GRBs. We also discuss characteristics of LAT-detected emission such as its delayed onset and longer duration compared with emission detected by the GBM, its power-law temporal decay at late times, and the fact that it is dominated by a power-law spectral component that appears in addition to the usual Band model.

  • 31. Ackermann, M.
    et al.
    Ajello, M.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Gonzalez, J. Becerra
    Bellazzini, R.
    Bialdi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bnino, R.
    Bottagini, E.
    Brandt, T. J.
    Bregeon, J.
    Britto, R. J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Careenter, B.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). The Royal Swedish Academy of Sciences, Sweden.
    Cutini, S.
    D'Abrusco, R.
    D'Ammando, F.
    de Angelis, A.
    Desiante, R.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Focke, W. B.
    Franckowiak, A.
    Fuhrmann, L.
    Fukazawa, Y.
    Furniss, A. K.
    Fusco, P.
    Gargano, E.
    Gasparrini, D.
    Giglietto, N.
    Giommi, P.
    Giordano, E.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Itoh, R.
    Jóhannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kataoka, J.
    Kawano, T.
    Krauss, F.
    Kuss, M.
    La Mura, G.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty of Science, Department of Astronomy.
    Latronico, L.
    Leto, C.
    Li, J.
    Li, Liang
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). KTH Royal Institute of Technology, Sweden.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nuss, E.
    Ohno, M.
    Oxsugi, T.
    Ojha, R.
    Omdei, N.
    Orienti, M.
    Orlando, E.
    Paggi, A.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Rainò, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Romani, R. W.
    Salvetti, D.
    Schaal, M.
    Schinzel, F. K.
    Schulz, A.
    Sgrò, C.
    Siskind, E. J.
    Sokolovsky, K. V.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Stawarz, L.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, Y.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Torres, D. F.
    Torresi, E.
    Tosti, G.
    Troja, E.
    Uchiyama, Y.
    Vianello, G.
    Winer, B. L.
    Wood, K. S.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    THE THIRD CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 810, no 1, 14Article in journal (Refereed)
    Abstract [en]

    The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100 MeV and 300 GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (vertical bar b vertical bar > 10 degrees), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.

  • 32. Ackermann, M.
    et al.
    Ajello, M.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Gonzalez, J. Becerra
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Brandt, T. J.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caputo, R.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Cohen, J. M.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Cuoco, A.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Desiante, R.
    Di Mauro, M.
    Di Venere, L.
    Dominguez, A.
    Drell, P. S.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fortin, P.
    Franckowiak, A.
    Fukazawa, Y.
    Funk, S.
    Furniss, A. K.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H.
    Guillemot, L.
    Guiriec, S.
    Harding, A. K.
    Hays, E.
    Hewitt, J. W.
    Hill, A. B.
    Horan, D.
    Iafrate, G.
    Hartmann, Dieter
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    La Mura, G.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Latronico, L.
    Lemoine-Goumard, M.
    Li, J.
    Li, Lang
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Maldera, S.
    Manfreda, A.
    Mayer, M.
    Mazziotta, M. N.
    Michelson, P. F.
    Mirabal, N.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Romani, R. W.
    Sánchez-Conde, Miguel
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Parkinson, P. M. Saz
    Schmid, J.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, M.
    Takahashi, T.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Troja, E.
    Vianello, G.
    Wood, K. S.
    Wood, M.
    Yassine, M.
    Zaharijas, G.
    Zimmer, Stephan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    2FHL: THE SECOND CATALOG OF HARD FERMI-LAT SOURCES2016In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 222, no 1, 5Article in journal (Refereed)
    Abstract [en]

    We present a catalog of sources detected above 50 GeV by the Fermi-Large Area Telescope (LAT) in 80 months of data. The newly delivered Pass. 8 event-level analysis allows the detection and characterization of sources in the 50 GeV-2 TeV energy range. In this energy band, Fermi-LAT. has detected 360 sources, which constitute the second catalog of hard Fermi-LAT. sources (2FHL). The improved angular resolution enables the precise localization of point sources (similar to 1.' 7 radius at 68% C.L.) and the detection and characterization of spatially extended sources. We find that 86% of the sources can be associated with counterparts at other wavelengths, of which the majority (75%) are active galactic nuclei and the rest (11%) are Galactic sources. Only 25% of the 2FHL sources have been previously detected by Cherenkov telescopes, implying that the 2FHL provides a reservoir of candidates to be followed up at very high energies. This work closes the energy gap between the observations performed at GeV energies by Fermi-LAT. on orbit and the observations performed at higher energies by Cherenkov telescopes from the ground.

  • 33. Ackermann, M.
    et al.
    Ajello, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Celik, Oe
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Corbel, S.
    Cutini, S.
    D'Ammando, F.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Escande, L.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Fuhrmann, L.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, Department of Astronomy. Stockholm University, Faculty of Science, Department of Physics.
    Latronico, L.
    Lee, S. -H
    Garde, Maja Llena
    Stockholm University, Faculty of Science, Department of Physics.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Marchili, N.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nalewajko, K.
    Naumann-Godo, M.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reyes, L. C.
    Ripken, Joachim
    Stockholm University, Faculty of Science, Department of Physics.
    Ritz, S.
    Roth, M.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Sander, A.
    Scargle, J. D.
    Sgro, C.
    Sikora, M.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Tanaka, Y.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Usher, T. L.
    Vandenbroucke, J.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Wehrle, A. E.
    Winer, B. L.
    Yang, Zhaoyu
    Stockholm University, Faculty of Science, Department of Physics.
    Ylinen, T.
    Ziegler, M.
    FERMI GAMMA-RAY SPACE TELESCOPE OBSERVATIONS OF GAMMA-RAY OUTBURSTS FROM 3C 454.3 IN 2009 DECEMBER AND 2010 APRIL2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 721, no 2, 1383-1396 p.Article in journal (Refereed)
    Abstract [en]

    The flat spectrum radio quasar 3C 454.3 underwent an extraordinary outburst in 2009 December when it became the brightest gamma-ray source in the sky for over 1 week. Its daily flux measured with the Fermi-Large Area Telescope at photon energiesE > 100 MeV reached F-100 = 22 +/- 1 x 10(6) photon cm(-2) s(-1), representing the highest daily flux of any blazar ever recorded in high-energy. -rays. It again became the brightest source in the sky in 2010 April, triggering a pointed-mode observation by Fermi. The correlated. -ray temporal and spectral properties during these exceptional events are presented and discussed. The main results show flux variability over time scales less than 3 hr and very mild spectral variability with an indication of gradual hardening preceding major flares. The light curves during periods of enhanced activity in 2008 July-August and 2010 December show strong resemblance, with a flux plateau of a few days preceding the major flare. No consistent loop pattern emerged in the. -ray spectral index versus the flux plane as would be expected in acceleration and cooling scenarios. The maximum energy of a photon from 3C 454.3 is approximate to 20 GeV and a minimum Doppler factor of approximate to 13 is derived. The gamma-ray spectrum of 3C 454.3 shows a significant spectral break between approximate to 2 and 3 GeV that is very weakly dependent on the flux state, even when the flux changes by an order of magnitude.

  • 34. Ackermann, M.
    et al.
    Ajello, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Gonzalez, J. Becerra
    Bellazzini, R.
    Bissaldi, E.
    Blandford, R. D.
    Bloom, E. D.
    Bonino, R.
    Bottacini, E.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Cameron, R. A.
    Caragiulo, M.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC).
    Costantin, D.
    Costanza, F.
    Cutini, S.
    D'Ammando, F.
    de Palma, F.
    Desiante, R.
    Digel, S. W.
    Di Lalla, N.
    Di Mauro, M.
    Di Venere, L.
    Dominguez, A.
    Drell, P. S.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Finke, J.
    Focke, W. B.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Green, D.
    Grenier, I. A.
    Guillemot, L.
    Guiriec, S.
    Hartmann, D. H.
    Hays, E.
    Horan, D.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kuss, M.
    La Mura, G.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). KTH Royal Institute of Technology, Sweden.
    Latronico, L.
    Li, J.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Magill, J. D.
    Maldera, S.
    Manfreda, A.
    Marcotulli, L.
    Mazziotta, M. N.
    Michelson, P. F.
    Mirabal, N.
    Mitthumsiri, W.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Negro, M.
    Nuss, E.
    Ohsugi, T.
    Ojha, R.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paliya, V. S.
    Paneque, D.
    Perkins, J. S.
    Persic, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Principe, G.
    Raino, S.
    Rando, R.
    Rani, B.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Romani, R. W.
    Sgro, C.
    Simone, D.
    Siskind, E. J.
    Spada, F.
    Spandre, G.
    Spinelli, P.
    Stalin, C. S.
    Stawarz, L.
    Suson, D. J.
    Takahashi, M.
    Tanaka, K.
    Thayer, J. B.
    Thompson, D. J.
    Torres, D. F.
    Torresi, E.
    Tosti, G.
    Troja, E.
    Vianello, G.
    Wood, K. S.
    Gamma-Ray Blazars within the First 2 Billion Years2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 837, no 1, L5Article in journal (Refereed)
    Abstract [en]

    The detection of high-redshift (z > 3) blazars enables the study of the evolution of the most luminous relativistic jets over cosmic time. More importantly, high-redshift blazars tend to host massive black holes and can be used to constrain the space density of heavy black holes in the early universe. Here, we report the first detection with the Fermi-Large Area Telescope of five gamma-ray-emitting blazars beyond z. =. 3.1, more distant than any blazars previously detected in.-rays gamma Among these five objects, NVSS J151002+570243 is now the most distant known gamma-ray-emitting blazar at z =. 4.31. These objects have steeply falling gamma-ray spectral energy distributions (SEDs), and. those that have been observed in X-rays have a very hard X-ray spectrum, both typical of powerful blazars. Their Compton dominance ( ratio of the inverse Compton to synchrotron peak luminosities) is also very large (>20). All of these properties place these objects among the most extreme members of the blazar population. Their optical spectra and the modeling of their optical-UV SEDs confirm that these objects harbor massive black holes (MBH similar to 10(8-10) M circle dot 8 10). We find that, at z approximate to 4, the space density of >10(9)M circle dot black holes hosted in radio-loud and radio-quiet active galactic nuclei are similar, implying that radio-loudness may play a key role in rapid black hole growth in the early universe.

  • 35. Ackermann, M.
    et al.
    Ajello, M.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bonamente, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, Jan
    Stockholm University, Faculty of Science, Department of Physics. Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Univ Udine, Dipartimento Fis, I-33100 Udine, Italy.
    Cutini, S.
    Dalton, M.
    D'Ammando, F.
    de Angelis, A.
    Den Hartog, P. R.
    de Palma, F.
    Dermer, C. D.
    Digel, S. W.
    Di Venere, L.
    Drell, P. S.
    Dubois, R.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Franckowiak, A.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hill, A. B.
    Horan, D.
    Hughes, R. E.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, T. J.
    Kawano, T.
    Kerr, M.
    Knoedlseder, J.
    Stockholm University, Faculty of Science, Department of Astronomy. st Nazl Fis Nucl, Sez Torino, I-10125 Turin, Italy.
    Kuss, M.
    Lande, J.
    Larsson, Stefan
    Stockholm University, Faculty of Science, The Oskar Klein Centre for Cosmo Particle Physics (OKC). Stockholm University, Faculty