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  • 1. Abdo, A. A.
    et al.
    Ackermann, M.
    Agudo, I.
    Ajello, M.
    Aller, H. D.
    Aller, M. F.
    Angelakis, E.
    Arkharov, A. A.
    Axelsson, Magnus
    Bach, U.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Baughman, B. M.
    Bechtol, K.
    Bellazzini, R.
    Benitez, E.
    Berdyugin, A.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Boettcher, M.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Burnett, T. H.
    Burrows, D.
    Buson, S.
    Caliandro, G. A.
    Calzoletti, L.
    Cameron, R. A.
    Capalbi, M.
    Caraveo, P. A.
    Carosati, D.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Celik, Oe.
    Charles, E.
    Chaty, S.
    Chekhtman, A.
    Chen, W. P.
    Chiang, J.
    Chincarini, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Colafrancesco, S.
    Cominsky, L. R.
    Conrad, J.
    Costamante, L.
    Cutini, S.
    D'ammando, F.
    Deitrick, R.
    D'Elia, V.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    Digel, S. W.
    Donnarumma, I.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dultzin, D.
    Dumora, D.
    Falcone, A.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Forne, E.
    Fortin, P.
    Frailis, M.
    Fuhrmann, L.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gomez, J. L.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giuliani, A.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Gronwall, C.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Gurwell, M. A.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Healey, S. E.
    Heidt, J.
    Hiriart, D.
    Horan, D.
    Hoversten, E. A.
    Hughes, R. E.
    Itoh, R.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Jorstad, S. G.
    Kadler, M.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kennea, J.
    Kerr, M.
    Kimeridze, G.
    Knoedlseder, J.
    Kocian, M. L.
    Kopatskaya, E. N.
    Koptelova, E.
    Konstantinova, T. S.
    Kovalev, Y. Y.
    Kovalev, Yu. A.
    Kurtanidze, O. M.
    Kuss, M.
    Lande, J.
    Larionov, V. M.
    Latronico, L.
    Leto, P.
    Lindfors, E.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Marchegiani, P.
    Marscher, A. P.
    Marshall, F.
    Max-Moerbeck, W.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Meurer, C.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nestoras, I.
    Nilsson, K.
    Nizhelsky, N. A.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Ojha, R.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Osborne, J.
    Ozaki, M.
    Pacciani, L.
    Padovani, P.
    Pagani, C.
    Page, K.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pasanen, M.
    Pavlidou, V.
    Pelassa, V.
    Pepe, M.
    Perri, M.
    Pesce-Rollins, M.
    Piranomonte, S.
    Piron, F.
    Pittori, C.
    Porter, T. A.
    Puccetti, S.
    Rahoui, F.
    Raino, S.
    Raiteri, C.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Richards, J. L.
    Ritz, S.
    Rochester, L. S.
    Rodriguez, A. Y.
    Romani, R. W.
    Ros, J. A.
    Roth, M.
    Roustazadeh, P.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sadun, A.
    Sanchez, D.
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Sellerholm, A.
    Sgro, C.
    Shaw, M. S.
    Sigua, L. A.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Stevenson, M.
    Stratta, G.
    Strickman, M. S.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Takalo, L. O.
    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.
    Verrecchia, F.
    Vilchez, N.
    Villata, M.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zensus, J. A.
    Zhekanis, G. V.
    Ziegler, M.
    The spectral energy distribution of fermi bright blazars2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 716, no 1, p. 30-70Article in journal (Refereed)
    Abstract [en]

    We have conducted a detailed investigation of the broadband spectral properties of the gamma-ray selected blazars of the Fermi LAT Bright AGN Sample (LBAS). By combining our accurately estimated Fermi gamma-ray spectra with Swift, radio, infra-red, optical, and other hard X-ray/gamma-ray data, collected within 3 months of the LBAS data taking period, we were able to assemble high-quality and quasi-simultaneous spectral energy distributions (SED) for 48 LBAS blazars. The SED of these gamma-ray sources is similar to that of blazars discovered at other wavelengths, clearly showing, in the usual log nu-log nu F-nu representation, the typical broadband spectral signatures normally attributed to a combination of low-energy synchrotron radiation followed by inverse Compton emission of one or more components. We have used these SED to characterize the peak intensity of both the low-and the high-energy components. The results have been used to derive empirical relationships that estimate the position of the two peaks from the broadband colors (i.e., the radio to optical, alpha(ro), and optical to X-ray, alpha(ox), spectral slopes) and from the gamma-ray spectral index. Our data show that the synchrotron peak frequency (nu(S)(peak)) is positioned between 10(12.5) and 10(14.5) Hz in broad-lined flat spectrum radio quasars (FSRQs) and between 10(13) and 10(17) Hz in featureless BL Lacertae objects. We find that the gamma-ray spectral slope is strongly correlated with the synchrotron peak energy and with the X-ray spectral index, as expected at first order in synchrotron-inverse Compton scenarios. However, simple homogeneous, one-zone, synchrotron self-Compton (SSC) models cannot explain most of our SED, especially in the case of FSRQs and low energy peaked (LBL) BL Lacs. More complex models involving external Compton radiation or multiple SSC components are required to reproduce the overall SED and the observed spectral variability. While more than 50% of known radio bright high energy peaked (HBL) BL Lacs are detected in the LBAS sample, only less than 13% of known bright FSRQs and LBL BL Lacs are included. This suggests that the latter sources, as a class, may be much fainter gamma-ray emitters than LBAS blazars, and could in fact radiate close to the expectations of simple SSC models. We categorized all our sources according to a new physical classification scheme based on the generally accepted paradigm for Active Galactic Nuclei and on the results of this SED study. Since the LAT detector is more sensitive to flat spectrum gamma-ray sources, the correlation between nu(S)(peak) and gamma-ray spectral index strongly favors the detection of high energy peaked blazars, thus explaining the Fermi overabundance of this type of sources compared to radio and EGRET samples. This selection effect is similar to that experienced in the soft X-ray band where HBL BL Lacs are the dominant type of blazars.

  • 2. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Allafort, A.
    Amin, M. A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brigida, M.
    Buehler, R.
    Bulmash, D.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Charles, E.
    Cheung, C. C.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    Corbet, R. H. D.
    Cutini, S.
    D'Ammando, F.
    de Angelis, A.
    de Palma, F.
    Dermer, C. D.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Finke, J.
    Focke, W. B.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Hughes, R. E.
    Inoue, Y.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics. Oskar Klein Centre for Cosmoparticle Physics, Sweden.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Mazziotta, M. N.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reyes, L. C.
    Ritz, S.
    Romoli, C.
    Roth, M.
    Parkinson, P. M. Saz
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Takahashi, H.
    Takeuchi, Y.
    Tanaka, T.
    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.
    Waite, A. P.
    Werner, M.
    Winer, B. L.
    Wood, K. S.
    Gamma-ray flaring activity from the gravitationally lensed blazar PKS 1830-211 observed by Fermi LAT2015In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 799, no 2, article id 143Article in journal (Refereed)
    Abstract [en]

    The Large Area Telescope ( LAT) on board the FermiGamma- ray Space Telescope routinely detects the MeV- peaked flat- spectrum radio quasar PKS 1830- 211 ( z = 2.507). Its apparent isotropic. - ray luminosity ( E > 100 MeV), averaged over 3 years of observations and peaking on 2010 October 14/ 15 at 2.9 x 1050 erg s- 1, makes it among the brightest high- redshift Fermi blazars. No published model with a single lens can account for all of the observed characteristics of this complex system. Based on radio observations, one expects time- delayed variability to follow about 25 days after a primary flare, with flux about a factor of 1.5 less. Two large. - ray flares of PKS 1830- 211 have been detected by the LAT in the considered period, and no substantial evidence for such a delayed activity was found. This allows us to place a lower limit of about 6 on the. - ray flux ratio between the two lensed images. Swift XRT observations from a dedicated Target of Opportunity program indicate a hard spectrum with no significant correlation of X- ray flux with the. - ray variability. The spectral energy distribution can be modeled with inverse Compton scattering of thermal photons from the dusty torus. The implications of the LAT data in terms of variability, the lack of evident delayed flare events, and different radio and. - ray flux ratios are discussed. Microlensing effects, absorption, size and location of the emitting regions, the complex mass distribution of the system, an energy- dependent inner structure of the source, and flux suppression by the lens galaxy for one image path may be considered as hypotheses for understanding our results.

  • 3. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Allafort, A.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Baughman, B. M.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, 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.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    Dermer, C. D.
    de Luca, A.
    de Palma, F.
    Dormody, M.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giavitto, G.
    Giebels, B.
    Giglietto, N.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hays, E.
    Hobbs, G.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S. -H
    Lemoine-Goumard, M.
    Garde, M. Llena
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Makeev, A.
    Manchester, R. N.
    Marelli, M.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    McGlynn, Sinead
    KTH, School of Engineering Sciences (SCI), Physics.
    Meurer, C.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nolan, P. L.
    Norris, J. P.
    Noutsos, A.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Ray, P. S.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Rochester, L. S.
    Rodriguez, A. Y.
    Romani, R. W.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sander, A.
    Parkinson, P. M. Saz
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Usher, T. L.
    Van Etten, A.
    Vasileiou, V.
    Venter, C.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Watters, K.
    Weltevrede, P.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics.
    Ziegler, M.
    THE VELA PULSAR: RESULTS FROM THE FIRST YEAR OF FERMI LAT OBSERVATIONS2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 713, no 1, p. 154-165Article in journal (Refereed)
    Abstract [en]

    We report on analysis of timing and spectroscopy of the Vela pulsar using 11 months of observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. The intrinsic brightness of Vela at GeV energies combined with the angular resolution and sensitivity of the LAT allows us to make the most detailed study to date of the energy-dependent light curves and phase-resolved spectra, using a LAT-derived timing model. The light curve consists of two peaks (P1 and P2) connected by bridge emission containing a third peak (P3). We have confirmed the strong decrease of the P1/P2 ratio with increasing energy seen with EGRET and previous Fermi LAT data, and observe that P1 disappears above 20 GeV. The increase with energy of the mean phase of the P3 component can be followed with much greater detail, showing that P3 and P2 are present up to the highest energies of pulsation. We find significant pulsed emission at phases outside the main profile, indicating that magnetospheric emission exists over 80% of the pulsar period. With increased high-energy counts the phase-averaged spectrum is seen to depart from a power law with simple exponential cutoff, and is better fit with a more gradual cutoff. The spectra in fixed-count phase bins are well fit with power laws with exponential cutoffs, revealing a strong and complex phase dependence of the cutoff energy, especially in the peaks. By combining these results with predictions of the outer magnetosphere models that map emission characteristics to phase, it will be possible to probe the particle acceleration and the structure of the pulsar magnetosphere with unprecedented detail.

  • 4. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Allafort, A.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bonamente, E.
    Borgland, A. W.
    Bouvier, A.
    Brandt, T. J.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Burnett, T. H.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe
    Chaty, S.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, J.
    Dermer, C. D.
    de Palma, F.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Frailis, M.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giordano, F.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hill, A. B.
    Horan, D.
    Hughes, R. E.
    Itoh, R.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S. -H
    Lemoine-Goumard, M.
    Livingstone, M.
    Garde, M. Llena
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Makeev, A.
    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.
    Nakamori, T.
    Naumann-Godo, M.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    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.
    Reposeur, T.
    Rodriguez, A. Y.
    Romani, R. W.
    Roth, M.
    Sadrozinski, H. F. -W
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wallace, E.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Z.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Fermi large area telescope observation of a gamma-ray source at the position of Eta Carinae2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 723, no 1, p. 649-657Article in journal (Refereed)
    Abstract [en]

    The Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope detected a gamma-ray source that is spatially consistent with the location of Eta Carinae. This source has been persistently bright since the beginning of the LAT survey observations (from 2008 August to 2009 July, the time interval considered here). The gamma-ray signal is detected significantly throughout the LAT energy band (i.e., up to similar to 100 GeV). The 0.1-100 GeV energy spectrum is well represented by a combination of a cutoff power-law model (<10 GeV) and a hard power-law component (>10 GeV). The total flux (>100 MeV) is 3.7(-0.1)(+0.3) x 10(-7) photons s(-1) cm(-2), with additional systematic uncertainties of 10%, and consistent with the average flux measured by AGILE. The light curve obtained by Fermi is consistent with steady emission. Our observations do not confirm the presence of a gamma-ray flare in 2008 October, as reported by Tavani et al., although we cannot exclude that a flare lasting only a few hours escaped detection by the Fermi LAT. We also do not find any evidence for gamma-ray variability that correlates with the large X-ray variability of Eta Carinae observed during 2008 December and 2009 January. We are thus not able to establish an unambiguous identification of the LAT source with Eta Carinae.

  • 5. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Antolini, E.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Carrigan, S.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Celik, Oe.
    Chekhtman, A.
    Chen, A. W.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Colafrancesco, S.
    Conrad, J.
    Cutini, S.
    Dermer, C. D.
    de Palma, F.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Frailis, M.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grandi, P.
    Grenier, I. A.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hayashida, M.
    Horan, D.
    Hughes, R. E.
    Itoh, R.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Mazziotta, M. N.
    McEnery, J. E.
    McGlynn, Sinead
    KTH, School of Engineering Sciences (SCI), Physics.
    Meurer, C.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nestoras, I.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    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.
    Reyes, L. C.
    Rodriguez, A. Y.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sambruna, R.
    Sander, A.
    Sato, R.
    Sgro, C.
    Shaw, M. S.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Stawarz, L.
    Stecker, F. W.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vasileiou, V.
    Vilchez, N.
    Villata, M.
    Vitale, V.
    von Kienlin, A.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Z.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics.
    Ziegler, M.
    Tavecchio, F.
    Sikora, M.
    Schady, P.
    Roming, P.
    Chester, M. M.
    Maraschi, L.
    SUZAKU OBSERVATIONS OF LUMINOUS QUASARS: REVEALING THE NATURE OF HIGH-ENERGY BLAZAR EMISSION IN LOW-LEVEL ACTIVITY STATES2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 716, no 1, p. 835-849Article in journal (Refereed)
    Abstract [en]

    We present the results from the Suzaku X-ray observations of five flat-spectrum radio quasars (FSRQs), namely PKS 0208-512, Q 0827+243, PKS 1127-145, PKS 1510-089, and 3C 454.3. All these sources were additionally monitored simultaneously or quasi-simultaneously by the Fermi satellite in gamma rays and the Swift UVOT in the UV and optical bands, respectively. We constructed their broadband spectra covering the frequency range from 10(14) Hz up to 10(25) Hz, and those reveal the nature of high-energy emission of luminous blazars in their low-activity states. The analyzed X-ray spectra are well fitted by a power-law model with photoelectric absorption. In the case of PKS 0208-512, PKS 1127-145, and 3C 454.3, the X-ray continuum showed indication of hardening at low energies. Moreover, when compared with the previous X-ray observations, we see a significantly increasing contribution of low-energy photons to the total X-ray fluxes when the sources are getting fainter. The same behavior can be noted in the Suzaku data alone. A likely explanation involves a variable, flat-spectrum component produced via inverse-Compton emission, plus an additional, possibly steady soft X-ray component prominent when the source gets fainter. This soft X-ray excess is represented either by a steep power-law (photon indices Gamma similar to 3-5) or a blackbody-type emission with temperatures kT similar to 0.1-0.2 keV. We model the broadband spectra of the five observed FSRQs using synchrotron self-Compton and/or external-Compton radiation models. Our modeling suggests that the difference between the low-and high-activity states in luminous blazars is due to the different total kinetic power of the jet, most likely related to varying bulk Lorentz factor of the outflow within the blazar emission zone.

  • 6. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Asano, K.
    Atwood, W. B.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    McGlynn, Sinéad
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    Fermi detection of delayed GeV emission from the short gamma-ray burst 081024B2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 712, no 1, p. 558-564Article in journal (Refereed)
    Abstract [en]

    We report on the detailed analysis of the high-energy extended emission from the short gamma-ray burst (GRB) 081024B detected by the Fermi Gamma-ray Space Telescope. Historically, this represents the first clear detection of temporal extended emission from a short GRB. The light curve observed by the Fermi Gamma-ray Burst Monitor lasts approximately 0.8 s whereas the emission in the Fermi Large Area Telescope lasts for about 3 s. Evidence of longer lasting high-energy emission associated with long bursts has been already reported by previous experiments. Our observations, together with the earlier reported study of the bright short GRB 090510, indicate similarities in the high-energy emission of short and long GRBs and open the path to new interpretations.

  • 7. 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, J.
    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.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jóhannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knödlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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.
    Rainò, 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.
    Sgrò, C.
    Share, G. H.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Stawarz, Ł.
    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, Z.
    Zimmer, S.
    Fermi observations of γ-ray emission from the moon2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 758, no 2, p. 140-Article in journal (Refereed)
    Abstract [en]

    We report on the detection of high-energy γ-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 2-3GeV, 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(&gt;cm -2s -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(&gt;100 MeV) ≈ 5 × 10 -7cm -2s -1, when solar activity was relatively high. The higher γ-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 γ-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 γ-ray sources. Analysis of the lunar and solar emission may thus be important for studies of weak and transient sources near the ecliptic.

  • 8. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Atwood, B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Bechtol, K.
    Belfiore, A.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Camilo, F.
    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, J.
    de Angelis, A.
    de Luca, A.
    de Palma, F.
    Digel, S. W.
    Dormody, M.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Edmonds, Y.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giavitto, G.
    Giglietto, N.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Gwon, C.
    Hadasch, D.
    Harding, A. K.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, R. P.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Kanai, Y.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Marelli, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Meurer, C.
    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.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Ransom, S. M.
    Ray, P. S.
    Razzano, M.
    Rea, N.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Rochester, L. S.
    Rodriguez, A. Y.
    Romani, R. W.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Thorsett, S. E.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Usher, T. L.
    Van Etten, A.
    Vasileiou, V.
    Venter, C.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Watters, K.
    Winer, B. L.
    Wolff, M. T.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Fermi large area telescope observations of PSR J1836+59252010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 712, no 2, p. 1209-1218Article in journal (Refereed)
    Abstract [en]

    The discovery of the gamma-ray pulsar PSR J1836+5925, powering the formerly unidentified EGRET source 3EG J1835+5918, was one of the early accomplishments of the Fermi Large Area Telescope (LAT). Sitting 25 degrees off the Galactic plane, PSR J1836+5925 is a 173 ms pulsar with a characteristic age of 1.8 million years, a spindown luminosity of 1.1 x 10(34) erg s(-1), and a large off-peak (OP) emission component, making it quite unusual among the known gamma-ray pulsar population. We present an analysis of one year of LAT data, including an updated timing solution, detailed spectral results, and a long-term light curve showing no indication of variability. No evidence for a surrounding pulsar wind nebula is seen and the spectral characteristics of the OP emission indicate it is likely magnetospheric. Analysis of recent XMM-Newton observations of the X-ray counterpart yields a detailed characterization of its spectrum, which, like Geminga, is consistent with that of a neutron star showing evidence for both magnetospheric and thermal emission.

  • 9. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Atwood, W. B.
    Axelsson, Magnus
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Baughman, B. M.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Camilo, F.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cognard, I.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, J.
    Corbet, R.
    Cutini, S.
    den Hartog, P. R.
    Dermer, C. D.
    de Angelis, A.
    de Luca, A.
    de Palma, F.
    Digel, S. W.
    Dormody, M.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Espinoza, C.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Freire, P. C. C.
    Fukazawa, Y.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giavitto, G.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Gotthelf, E. V.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Gwon, C.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, R. P.
    Johnson, T. J.
    Johnson, W. N.
    Johnston, S.
    Kamae, T.
    Kanbach, G.
    Kaspi, V. M.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kerr, M.
    Knoedlseder, J.
    Kocian, M. L.
    Kramer, M.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lemoine-Goumard, M.
    Livingstone, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Lyne, A. G.
    Madejski, G. M.
    Makeev, A.
    Manchester, R. N.
    Marelli, M.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    McGlynn, Sinéad
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Meurer, C.
    Michelson, P. F.
    Mineo, T.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nakamori, T.
    Nolan, P. L.
    Norris, J. P.
    Noutsos, A.
    Nuss, E.
    Ohsugi, T.
    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.
    Ransom, S. M.
    Ray, P. S.
    Razzano, M.
    Rea, N.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Rodriguez, A. Y.
    Romani, R. W.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schalk, T. L.
    Sellerholm, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Stappers, B. W.
    Starck, J. -L
    Striani, E.
    Strickman, M. S.
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Theureau, G.
    Thompson, D. J.
    Thorsett, S. E.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Van Etten, A.
    Vasileiou, V.
    Venter, C.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Wang, N.
    Watters, K.
    Weltevrede, P.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    The first fermi large area telescope catalog of gamma-ray pulsars2010In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 187, no 2, p. 460-494Article in journal (Refereed)
    Abstract [en]

    The dramatic increase in the number of known gamma-ray pulsars since the launch of the Fermi Gamma-ray Space Telescope (formerly GLAST) offers the first opportunity to study a sizable population of these high-energy objects. This catalog summarizes 46 high-confidence pulsed detections using the first six months of data taken by the Large Area Telescope (LAT), Fermi's main instrument. Sixteen previously unknown pulsars were discovered by searching for pulsed signals at the positions of bright gamma-ray sources seen with the LAT, or at the positions of objects suspected to be neutron stars based on observations at other wavelengths. The dimmest observed flux among these gamma-ray-selected pulsars is 6.0 x 10(-8) ph cm(-2) s(-1) (for E > 100 MeV). Pulsed gamma-ray emission was discovered from 24 known pulsars by using ephemerides (timing solutions) derived from monitoring radio pulsars. Eight of these new gamma-ray pulsars are millisecond pulsars. The dimmest observed flux among the radio-selected pulsars is 1.4 x 10(-8) ph cm(-2) s(-1) (for E > 100 MeV). The remaining six gamma-ray pulsars were known since the Compton Gamma Ray Observatory mission, or before. The limiting flux for pulse detection is non-uniform over the sky owing to different background levels, especially near the Galactic plane. The pulsed energy spectra can be described by a power law with an exponential cutoff, with cutoff energies in the range similar to 1-5 GeV. The rotational energy-loss rate ((E) over dot) of these neutron stars spans five decades, from similar to 3 x 10(33) erg s(-1) to 5 x 10(38) erg s(-1), and the apparent efficiencies for conversion to gammaray emission range from similar to 0.1% to similar to unity, although distance uncertainties complicate efficiency estimates. The pulse shapes show substantial diversity, but roughly 75% of the gamma-ray pulse profiles have two peaks, separated by greater than or similar to 0.2 of rotational phase. For most of the pulsars, gamma-ray emission appears to come mainly from the outer magnetosphere, while polar-cap emission remains plausible for a remaining few. Spatial associations imply that many of these pulsars power pulsar wind nebulae. Finally, these discoveries suggest that gamma-ray-selected young pulsars are born at a rate comparable to that of their radio-selected cousins and that the birthrate of all young gamma-ray-detected pulsars is a substantial fraction of the expected Galactic supernova rate.

  • 10. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Baughman, B. M.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bouvier, A.
    Brandt, T. J.
    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.
    Cavazzuti, E.
    Cecchi, C.
    Celik, Oe
    Charles, E.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Colafrancesco, S.
    Cominsky, L. R.
    Conrad, J.
    Costamante, L.
    Davis, D. S.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Dumora, D.
    Falcone, A.
    Farnier, C.
    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.
    Georganopoulos, M.
    Germani, S.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grandi, P.
    Grenier, I. A.
    Grondin, M. -H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Harding, A. K.
    Hase, Hayo
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Itoh, R.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Kadler, M.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kishishita, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S. -H
    Lemoine-Goumard, M.
    Garde, M. Llena
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    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.
    Mueller, C.
    Nakamori, T.
    Naumann-Godo, M.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Ojha, R.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Ozaki, M.
    Pagani, C.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Plotz, C.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ripken, J.
    Ritz, S.
    Rodriguez, A. Y.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Sander, A.
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Stawarz, 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.
    Vandenbroucke, J.
    Vasileiou, V.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Z.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    FERMI LARGE AREA TELESCOPE VIEW OF THE CORE OF THE RADIO GALAXY CENTAURUS A2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 719, no 2, p. 1433-1444Article in journal (Refereed)
    Abstract [en]

    We present gamma-ray observations with the Large Area Telescope (LAT) on board the Fermi Gamma-Ray Space Telescope of the nearby radio galaxy Centaurus A (Cen A). The previous EGRET detection is confirmed, and the localization is improved using data from the first 10 months of Fermi science operation. In previous work, we presented the detection of the lobes by the LAT; in this work, we concentrate on the gamma-ray core of Cen A. Flux levels as seen by the LAT are not significantly different from that found by EGRET, nor is the extremely soft LAT spectrum (Gamma = 2.67 +/- 0.10(stat) +/- 0.08(sys) where the photon flux is Phi alpha E-Gamma). The LAT core spectrum, extrapolated to higher energies, is marginally consistent with the non-simultaneous HESS spectrum of the source. The LAT observations are complemented by simultaneous observations from Suzaku, the Swift Burst Alert Telescope and X-ray Telescope, and radio observations with the Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry program, along with a variety of non-simultaneous archival data from a variety of instruments and wavelengths to produce a spectral energy distribution (SED). We fit this broadband data set with a single-zone synchrotron/synchrotron self-Compton model, which describes the radio through GeV emission well, but fails to account for the non-simultaneous higher energy TeV emission observed by HESS from 2004 to 2008. The fit requires a low Doppler factor, in contrast to BL Lac objects which generally require larger values to fit their broadband SEDs. This indicates that the gamma-ray emission originates from a slower region than that from BL Lac objects, consistent with previous modeling results from Cen A. This slower region could be a slower moving layer around a fast spine, or a slower region farther out from the black hole in a decelerating flow. The fit parameters are also consistent with Cen A being able to accelerate ultra-high energy cosmic-rays, as hinted at by results from the Auger observatory.

  • 11. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    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.
    Caraveo, P. A.
    Carrigan, S.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe.
    Chekhtman, A.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Dumora, D.
    Edmonds, Y.
    Essig, R.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. 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.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Harding, A. K.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, R. P.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Garde, M. Llena
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Makeev, A.
    Mazziotta, M. N.
    McEnery, J. E.
    Meurer, C.
    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.
    Ozaki, M.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ripken, J.
    Ritz, S.
    Rodriguez, A. Y.
    Roth, M.
    Sadrozinski, H. F. -W
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schalk, T. L.
    Sellerholm, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Starck, J. -L
    Strickman, M. S.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Tibaldo, L.
    Torres, D. F.
    Uchiyama, Y.
    Usher, T. L.
    Vasileiou, V.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Fermi Large Area Telescope Search for Photon Lines from 30 to 200 GeV and Dark Matter Implications2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 9, p. 091302-Article in journal (Refereed)
    Abstract [en]

    Dark matter (DM) particle annihilation or decay can produce monochromatic gamma rays readily distinguishable from astrophysical sources. gamma- ray line limits from 30 to 200 GeV obtained from 11 months of Fermi Large Area Space Telescope data from 20-300 GeV are presented using a selection based on requirements for a gamma-ray line analysis, and integrated over most of the sky. We obtain gamma-ray line flux upper limits in the range 0.6-4.5 x 10(-9) cm(-2) s(-1), and give corresponding DM annihilation cross-section and decay lifetime limits. Theoretical implications are briefly discussed.

  • 12. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Atwood, W. B.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Burnett, T. H.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    de Angelis, A.
    de Palma, F.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Dumora, D.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gehrels, N.
    Germani, S.
    Giebels, B.
    Giglietto, N.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Gustafsson, M.
    Harding, A. K.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jeltema, T. E.
    Johannesson, G.
    Johnson, A. S.
    Johnson, R. P.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Mazziotta, M. N.
    McEnery, J. E.
    Meurer, C.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Moretti, Elena
    University and INFN of Trieste.
    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.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Profumo, S.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ritz, S.
    Rodriguez, A. Y.
    Roth, M.
    Sadrozinski, H. F. -W
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Schalk, T. L.
    Sellerholm, A.
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Thayer, J. B.
    Thayer, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vasileiou, V.
    Vilchez, N.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Bullock, James S.
    Kaplinghat, Manoj
    Martinez, Gregory D.
    Observations of Milky way dwarf spheroidal galaxies with the Fermi-large area telescope detector and constraints on dark matter models2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 712, no 1, p. 147-158Article in journal (Refereed)
    Abstract [en]

    We report on the observations of 14 dwarf spheroidal galaxies (dSphs) with the Fermi Gamma-Ray Space Telescope taken during the first 11 months of survey mode operations. The Fermi telescope, which is conducting an all-sky gamma-ray survey in the 20 MeV to > 300 GeV energy range, provides a new opportunity to test particle dark matter models through the expected gamma-ray emission produced by pair annihilation of weakly interacting massive particles (WIMPs). Local Group dSphs, the largest galactic substructures predicted by the cold dark matter scenario, are attractive targets for such indirect searches for dark matter because they are nearby and among the most extreme dark matter dominated environments. No significant gamma-ray emission was detected above 100 MeV from the candidate dwarf galaxies. We determine upper limits to the gamma-ray flux assuming both power-law spectra and representative spectra from WIMP annihilation. The resulting integral flux above 100 MeV is constrained to be at a level below around 10(-9) photons cm(-2) s(-1). Using recent stellar kinematic data, the gamma-ray flux limits are combined with improved determinations of the dark matter density profile in eight of the 14 candidate dwarfs to place limits on the pair-annihilation cross section of WIMPs in several widely studied extensions of the standard model, including its supersymmetric extension and other models that received recent attention. With the present data, we are able to rule out large parts of the parameter space where the thermal relic density is below the observed cosmological dark matter density and WIMPs (neutralinos here) are dominantly produced non-thermally, e. g., in models where supersymmetry breaking occurs via anomaly mediation. The gamma-ray limits presented here also constrain some WIMP models proposed to explain the Fermi and PAMELA e(+)e(-) data, including low-mass wino-like neutralinos and models with TeV masses pair annihilating into muon-antimuon pairs.

  • 13. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Axelsson, Magnus
    Johannesson, G.
    Johnson, A. S.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Wagner, S.
    Conrad, Jan
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Mc Glynn, Sinéad
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    MULTIWAVELENGTH MONITORING OF THE ENIGMATIC NARROW-LINE SEYFERT 1 PMN J0948+0022 IN 2009 MARCH-JULY2009In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 707, no 1, p. 727-737Article in journal (Refereed)
    Abstract [en]

    Following the recent discovery of gamma rays from the radio-loud narrow-line Seyfert 1 galaxy PMN J0948+0022 (z = 0.5846), we started a multiwavelength campaign from radio to gamma rays, which was carried out between the end of 2009 March and the beginning of July. The source displayed activity at all the observed wavelengths: a general decreasing trend from optical to gamma-ray frequencies was followed by an increase of radio emission after less than two months from the peak of the gamma-ray emission. The largest flux change, about a factor of about 4, occurred in the X-ray band. The smallest was at ultraviolet and near-infrared frequencies, where the rate of the detected photons dropped by a factor 1.6-1.9. At optical wavelengths, where the sampling rate was the highest, it was possible to observe day scale variability, with flux variations up to a factor of about 3. The behavior of PMN J0948+0022 observed in this campaign and the calculated power carried out by its jet in the form of protons, electrons, radiation, and magnetic field are quite similar to that of blazars, specifically of flat-spectrum radio quasars. These results confirm the idea that radio-loud narrow-line Seyfert 1 galaxies host relativistic jets with power similar to that of average blazars.

  • 14. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Axelsson, Magnus
    Johannesson, G.
    Johnson, A. S.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Conrad, Jan
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Modulated High-Energy Gamma-Ray Emission from the Microquasar Cygnus X-32009In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 326, no 5959, p. 1512-1516Article in journal (Refereed)
    Abstract [en]

    Microquasars are accreting black holes or neutron stars in binary systems with associated relativistic jets. Despite their frequent outburst activity, they have never been unambiguously detected emitting high-energy gamma rays. The Fermi Large Area Telescope (LAT) has detected a variable high-energy source coinciding with the position of the x-ray binary and microquasar Cygnus X-3. Its identification with Cygnus X-3 is secured by the detection of its orbital period in gamma rays, as well as the correlation of the LAT flux with radio emission from the relativistic jets of Cygnus X-3. The gamma-ray emission probably originates from within the binary system, opening new areas in which to study the formation of relativistic jets.

  • 15. 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.
    Brandt, T. J.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    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
    Celotti, A.
    Charles, E.
    Chekhtman, A.
    Chen, A. W.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Colafrancesco, S.
    Conrad, J.
    Davis, D. S.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    do Couto e Silva, E.
    Drell, P. S.
    Dubois, R.
    Favuzzi, C.
    Fegan, S. J.
    Ferrara, E. C.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grandi, P.
    Grenier, I. A.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S-H
    Lemoine-Goumard, M.
    Garde, M. Llena
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Malaguti, G.
    Mazziotta, M. N.
    McConville, W.
    McEnery, J. E.
    Michelson, P. F.
    Migliori, G.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Nestoras, I.
    Nolan, P. L.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Okumura, A.
    Omodei, N.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Persic, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Reyes, L. C.
    Roth, M.
    Sadrozinski, H. F-W
    Sanchez, D.
    Sander, A.
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Stawarz, L.
    Stecker, F. W.
    Strickman, M. S.
    Suson, D. J.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. B.
    Thaver, J. G.
    Thompson, D. J.
    Tibaldo, L.
    Torres, D. F.
    Torresi, E.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vilchez, N.
    Villata, M.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Yang, Z.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Fermi Large Area Telescope observations of misaligned active galactic nuclei2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 720, no 1, p. 912-922Article in journal (Refereed)
    Abstract [en]

    Analysis is presented for 15 months of data taken with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope for 11 non-blazar active galactic nuclei (AGNs), including seven FRI radio galaxies and four FRII radio sources consisting of two FRII radio galaxies and two steep spectrum radio quasars. The broad line FRI radio galaxy 3C 120 is reported here as a gamma-ray source for the first time. The analysis is based on directional associations of LAT sources with radio sources in the 3CR, 3CRR, and MS4 (collectively referred to as 3C-MS) catalogs. Seven of the eleven LAT sources associated with 3C-MS radio sources have spectral indices larger than 2.3 and, except for the FRI radio galaxy NGC 1275 that shows possible spectral curvature, are well described by a power law. No evidence for time variability is found for any sources other than NGC 1275. The gamma-ray luminosities of FRI radio galaxies are significantly smaller than those of the BL Lac objects detected by the LAT, whereas the gamma-ray luminosities of the FRII sources are quite similar to those of FSRQs, which could reflect different beaming factors for the gamma-ray emission. A core dominance (CD) study of the 3CRR sample indicates that sources closer to the jet axis are preferentially detected with the Fermi LAT, insofar as the gamma-ray-detected misaligned AGNs have larger CD at a given average radio flux. The results are discussed in view of the AGN unification scenario.

  • 16. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bouvier, A.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cecchi, C.
    Celik, Oe
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    Dermer, C. D.
    de Palma, F.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Dumora, D.
    Favuzzi, C.
    Funk, S.
    Fusco, P.
    Gargano, F.
    Gehrels, N.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grondin, M-H
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Harding, A. K.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Katsuta, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lee, S-H
    Lemoine-Goumard, M.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Makeev, A.
    Mazziotta, M. N.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    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.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Ripken, J.
    Roth, M.
    Sadrozinski, H. FW.
    Sander, A.
    Parkinson, P. M. Saz
    Sgro, C.
    Siskind, E. J.
    Smith, D. A.
    Smith, P. D.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Takahashi, T.
    Tanaka, T.
    Tibaldo, L.
    Tibolla, O.
    Torres, D. F.
    Tosti, G.
    Tramacere, A.
    Uchiyama, Y.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vitale, V.
    Waite, A. P.
    Wang, P.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Fermi-LAT study of Gamma-ray emission in the direction of supernova remnant W49B2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 722, no 2, p. 1303-1311Article in journal (Refereed)
    Abstract [en]

    We present an analysis of the gamma-ray data obtained with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope in the direction of SNR W49B (G43.3-0.2). A bright unresolved gamma-ray source detected at a significance of 38 sigma is found to coincide with SNR W49B. The energy spectrum in the 0.2-200 GeV range gradually steepens toward high energies. The luminosity is estimated to be 1.5 x 10(36) (D/8 kpc)(2) erg s(-1) in this energy range. There is no indication that the gamma-ray emission comes from a pulsar. Assuming that the supernova remnant (SNR) shell is the site of gamma-ray production, the observed spectrum can be explained either by the decay of neutral pi mesons produced through the proton-proton collisions or by electron bremsstrahlung. The calculated energy density of relativistic particles responsible for the LAT flux is estimated to be remarkably large, U-e,U-p > 10(4) eV cm(-3), for either gamma-ray production mechanism.

  • 17. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    Fermi observations of cassiopeia and cepheus: Diffuse gamma-ray emission in the outer galaxy2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 710, no 1, p. 133-149Article in journal (Refereed)
    Abstract [en]

    We present the analysis of the interstellar gamma-ray emission measured by the Fermi Large Area Telescope toward a region in the second Galactic quadrant at 100 degrees <= l <= 145 degrees and -15 degrees <= b <= +30 degrees. This region encompasses the prominent Gould Belt clouds of Cassiopeia, Cepheus, and the Polaris flare, as well as atomic and molecular complexes at larger distances, like that associated with NGC 7538 in the Perseus arm. The good kinematic separation in velocity between the local, Perseus, and outer arms, and the presence of massive complexes in each of them, make this region well suited to probe cosmic rays (CRs) and the interstellar medium beyond the solar circle. The gamma-ray emissivity spectrum of the gas in the Gould Belt is consistent with expectations based on the locally measured CR spectra. The gamma-ray emissivity decreases from the Gould Belt to the Perseus arm, but the measured gradient is flatter than expectations for CR sources peaking in the inner Galaxy as suggested by pulsars. The X-CO = N(H-2)/W-CO conversion factor is found to increase from (0.87 +/- 0.05) x 10(20) cm(-2) (K km s(-1))(-1) in the Gould Belt to (1.9 +/- 0.2) x 10(20) cm(-2) (K km s(-1))(-1) in the Perseus arm. We derive masses for the molecular clouds under study. Dark gas, not properly traced by radio and microwave surveys, is detected in the Gould Belt through a correlated excess of dust and gamma-ray emission: its mass amounts to similar to 50% of the CO-traced mass.

  • 18. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    Gamma-Ray Emission from the Shell of Supernova Remnant W44 Revealed by the Fermi LAT2010In: Science, ISSN 0036-8075, E-ISSN 1095-9203, Vol. 327, no 5969, p. 1103-1106Article in journal (Refereed)
    Abstract [en]

    Recent observations of supernova remnants (SNRs) hint that they accelerate cosmic rays to energies close to similar to 10(15) electron volts. However, the nature of the particles that produce the emission remains ambiguous. We report observations of SNR W44 with the Fermi Large Area Telescope at energies between 2 x 10(8) electron volts and 3 x 10(11) electron volts. The detection of a source with a morphology corresponding to the SNR shell implies that the emission is produced by particles accelerated there. The gamma-ray spectrum is well modeled with emission from protons and nuclei. Its steepening above similar to 10(9) electron volts provides a probe with which to study how particle acceleration responds to environmental effects such as shock propagation in dense clouds and how accelerated particles are released into interstellar space.

  • 19. Abdo, A. A.
    et al.
    Ackermann, M.
    Ajello, M.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    OBSERVATION OF SUPERNOVA REMNANT IC 443 WITH THE FERMI LARGE AREA TELESCOPE2010In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 712, no 1, p. 459-468Article in journal (Refereed)
    Abstract [en]

    We report observation of the supernova remnant (SNR) IC 443 (G189.1+3.0) with the Fermi Gamma-ray Space Telescope Large Area Telescope (LAT) in the energy band between 200 MeV and 50 GeV. IC 443 is a shell-type SNR with mixed morphology located off the outer Galactic plane where high-energy emission has been detected in the X-ray, GeV and TeV gamma-ray bands. Past observations suggest IC 443 has been interacting with surrounding interstellar matter. Proximity between dense shocked molecular clouds and GeV-TeV gamma-ray emission regions detected by EGRET, MAGIC, and VERITAS suggests an interpretation that cosmic-ray (CR) particles are accelerated by the SNR. With the high gamma-ray statistics and broad energy coverage provided by the LAT, we accurately characterize the gamma-ray emission produced by the CRs accelerated at IC 443. The emission region is extended in the energy band with theta(68) = 0 degrees.27 +/- 0 degrees.01(stat) +/- 0 degrees.03(sys) for an assumed two-dimensional Gaussian profile and overlaps almost completely with the extended source region of VERITAS. Its centroid is displaced significantly from the known pulsar wind nebula (PWN) which suggests the PWN is not the major contributor in the present energy band. The observed spectrum changes its power-law slope continuously and continues smoothly to the MAGIC and VERITAS data points. The combined gamma-ray spectrum (200 MeV < E < 2 TeV) is reproduced well by decays of neutral pions produced by a broken power-law proton spectrum with a break around 70 GeV.

  • 20. 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.
    Çelik, Ö.
    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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Janssen, G. H.
    Jogler, T.
    Jóhannesson, G.
    Johnson, R. P.
    Johnson, A. S.
    Johnson, T. J.
    Johnson, W. N.
    Johnston, S.
    Kamae, T.
    Kataoka, J.
    Keith, M.
    Kerr, M.
    Knödlseder, J.
    Kramer, M.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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.
    Rainò, 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.
    Saz Parkinson, P. M.
    Scargle, J. D.
    Schulz, A.
    Sgrò, 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, Z.
    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 2, p. 17-Article 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.

  • 21. Abdo, A. A.
    et al.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    McGlynn, Sinéad
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    THE FIRST FERMI LARGE AREA TELESCOPE CATALOG OF GAMMA-RAY PULSARS (vol 187, pg 460, 2010)2011In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 193, no 1Article in journal (Refereed)
  • 22. Abdo, A. A.
    et al.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    Fermi LAT discovery of extended gamma-ray emission in the direction of supernova remnant W51C2009In: ASTROPHYSICAL JOURNAL LETTERS, ISSN 2041-8205, Vol. 706, no 1, p. L1-L6Article in journal (Refereed)
    Abstract [en]

    The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) onboard the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant (similar to 10(4) yr) with intense radio synchrotron emission in its shell and known to be interacting with a molecular cloud. The gamma-ray emission is spatially extended, broadly consistent with the radio and X-ray extent of SNR W51C. The energy spectrum in the 0.2-50 GeV band exhibits steepening toward high energies. The luminosity is greater than 1 x 10(36) erg s(-1) given the distance constraint of D > 5.5 kpc, which makes this object one of the most luminous gamma-ray sources in our Galaxy. The observed gamma-rays can be explained reasonably by a combination of efficient acceleration of nuclear cosmic rays at supernova shocks and shock-cloud interactions. The decay of neutral pi mesons produced in hadronic collisions provides a plausible explanation for the gamma-ray emission. The product of the average gas density and the total energy content of the accelerated protons amounts to (n) over bar W-H(p) similar or equal to 5 x 10(51) (D/6 kpc)(2) erg cm(-3). Electron density constraints from the radio and X-ray bands render it difficult to explain the LAT signal as due to inverse Compton scattering. The Fermi LAT source coincident with SNR W51C sheds new light on the origin of Galactic cosmic rays.

  • 23. Abdo, A. A.
    et al.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    et al.,
    OBSERVATIONS OF THE YOUNG SUPERNOVA REMNANT RX J1713.7-3946 WITH THE FERMI LARGE AREA TELESCOPE2011In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 734, no 1Article in journal (Refereed)
    Abstract [en]

    We present observations of the young supernova remnant (SNR) RX J1713.7-3946 with the Fermi Large Area Telescope (LAT). We clearly detect a source positionally coincident with the SNR. The source is extended with a best-fit extension of 0 degrees.55 +/- 0 degrees.04 matching the size of the non-thermal X-ray and TeV gamma-ray emission from the remnant. The positional coincidence and the matching extended emission allow us to identify the LAT source with SNR RX J1713.7-3946. The spectrum of the source can be described by a very hard power law with a photon index of Gamma = 1.5 +/- 0.1 that coincides in normalization with the steeper H. E. S. S.-detected gamma-ray spectrum at higher energies. The broadband gamma-ray emission is consistent with a leptonic origin as the dominant mechanism for the gamma-ray emission.

  • 24. Abdo, A.A.
    et al.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    et al.,
    Fermi-lat discovery of gev gamma-ray emission from the young supernova remnant cassiopeia A2010In: Astrophysical Journal Letters, ISSN 2041-8205, Vol. 710, no 1, p. L92-L97Article in journal (Refereed)
    Abstract [en]

    We report on the first detection of GeV high-energy gamma-ray emission from a young supernova remnant (SNR) with the Large Area Telescope aboard the Fermi Gamma-ray Space Telescope. These observations reveal a source with no discernible spatial extension detected at a significance level of 12.2 sigma above 500 MeV a a location that is consistent with the position of the remnant of the supernova explosion that occurred around 1680 in the Cassiopeia constellation-Cassiopeia A (Cas A). The gamma-ray flux and spectral shape of the source are consistent with a scenario in which the gamma-ray emission originates from relativistic particles accelerated in the shell of this remnant. The total content of cosmic rays (electrons and protons) accelerated in Cas A can be estimated as W(CR) similar or equal to (1-4) x 10(49) erg thanks to the well-known density in the remnant assuming that the observed gamma ray originates in the SNR shell(s). The magnetic field in the radio-emitting plasma can be robustly constrained as B >= 0.1 mG, providing new evidence of the magnetic field amplification at the forward shock and the strong field in the shocked ejecta.

  • 25. Acciari, V. A.
    et al.
    Aliu, E.
    Arlen, T.
    Aune, T.
    Bautista, M.
    Beilicke, M.
    Benbow, W.
    Boettcher, M.
    Boltuch, D.
    Bradbury, S. M.
    Buckley, J. H.
    Bugaev, V.
    Byrum, K.
    Cannon, A.
    Cesarini, A.
    Chow, Y. C.
    Ciupik, L.
    Cogan, P.
    Cui, W.
    Duke, C.
    Falcone, A.
    Finley, J. P.
    Finnegan, G.
    Fortson, L.
    Furniss, A.
    Galante, N.
    Gall, D.
    Gillanders, G. H.
    Godambe, S.
    Grube, J.
    Guenette, R.
    Gyuk, G.
    Hanna, D.
    Holder, J.
    Hui, C. M.
    Humensky, T. B.
    Kaaret, P.
    Karlsson, N.
    Kertzman, M.
    Kieda, D.
    Konopelko, A.
    Krawczynski, H.
    Krennrich, F.
    Lang, M. J.
    LeBohec, S.
    Maier, G.
    McArthur, S.
    McCann, A.
    McCutcheon, M.
    Millis, J.
    Moriarty, P.
    Nagai, T.
    Ong, R. A.
    Otte, A. N.
    Pandel, D.
    Perkins, J. S.
    Pichel, A.
    Pohl, M.
    Quinn, J.
    Ragan, K.
    Reyes, L. C.
    Reynolds, P. T.
    Roache, E.
    Rose, H. J.
    Schroedter, M.
    Sembroski, G. H.
    Senturk, G. Demet
    Smith, A. W.
    Steele, D.
    Swordy, S. P.
    Theiling, M.
    Thibadeau, S.
    Varlotta, A.
    Vassiliev, V. V.
    Vincent, S.
    Wagner, R. G.
    Wakely, S. P.
    Ward, J. E.
    Weekes, T. C.
    Weinstein, A.
    Weisgarber, T.
    Williams, D. A.
    Wissel, S.
    Wood, M.
    Zitzer, B.
    Abdo, A. A.
    Ackermann, M.
    Ajello, M.
    Baldini, L.
    Ballet, J.
    Barbiellini, G.
    Bastieri, D.
    Baughman, B. M.
    Bechtol, K.
    Bellazzini, R.
    Berenji, B.
    Blandford, R. D.
    Bloom, E. D.
    Bonamente, E.
    Borgland, A. W.
    Bregeon, J.
    Brez, A.
    Brigida, M.
    Bruel, P.
    Burnett, T. H.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Casandjian, J. M.
    Cavazzuti, E.
    Cecchi, C.
    Celik, Oe
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    Cutini, S.
    Dermer, C. D.
    de Angelis, A.
    de Palma, F.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Dubois, R.
    Dumora, D.
    Farnier, C.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Fortin, P.
    Frailis, M.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Germani, S.
    Giebels, B.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guillemot, L.
    Guiriec, S.
    Hanabata, Y.
    Hays, E.
    Hughes, R. E.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kawai, N.
    Kerr, M.
    Knoedlseder, J.
    Kocian, M. L.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Madejski, G. M.
    Makeev, A.
    Mazziotta, M. N.
    McEnery, J. E.
    Meurer, C.
    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.
    Parent, D.
    Pelassa, V.
    Pepe, M.
    Pesce-Rollins, M.
    Piron, F.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Reposeur, T.
    Rodriguez, A. Y.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sadrozinski, H. F. -W
    Sanchez, D.
    Sander, A.
    Parkinson, P. M. Saz
    Scargle, J. D.
    Sgro, C.
    Shaw, M. S.
    Siskind, E. J.
    Smith, P. D.
    Spandre, G.
    Spinelli, P.
    Strickman, M. S.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    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.
    Winer, B. L.
    Wood, K. S.
    Ylinen, Tomi
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Ziegler, M.
    Barber, S. D.
    Terndrup, D. M.
    Discovery of very high energy gamma rays from PKS 1424+240 and multiwavelength constraints on ITS redshift2010In: ASTROPHYSICAL JOURNAL LETTERS, ISSN 2041-8205, Vol. 708, no 2, p. L100-L106Article in journal (Refereed)
    Abstract [en]

    We report the first detection of very high energy(83) (VHE) gamma-ray emission above 140 GeV from PKS 1424+240, a BL Lac object with an unknown redshift. The photon spectrum above 140 GeV measured by VERITAS is well described by a power law with a photon index of 3.8 +/- 0.5(stat) +/- 0.3(syst) and a flux normalization at 200 GeV of (5.1 +/- 0.9(stat) +/- 0.5(syst)) x 10(-11) TeV-1 cm(-2) s(-1), where stat and syst denote the statistical and systematical uncertainties, respectively. The VHE flux is steady over the observation period between MJD 54881 and 55003 (from 2009 February 19 to June 21). Flux variability is also not observed in contemporaneous high-energy observations with the Fermi Large Area Telescope. Contemporaneous X-ray and optical data were also obtained from the Swift XRT and MDM observatory, respectively. The broadband spectral energy distribution is well described by a one-zone synchrotron self-Compton model favoring a redshift of less than 0.1. Using the photon index measured with Fermi in combination with recent extragalactic background light absorption models it can be concluded from the VERITAS data that the redshift of PKS 1424+240 is less than 0.66.

  • 26. 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, J.
    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.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kawano, T.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, Z.
    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, p. 77-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.

  • 27. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, W. N.
    Kamae, T.
    Kataoka, J.
    Kawano, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, Z.
    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, p. 57-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.

  • 28. Ackermann, M.
    et al.
    Ajello, M.
    Albert, A.
    Allafort, A.
    Atwood, W. B.
    Axelsson, Magnus
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    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.
    Çelik, Ö.
    Charles, E.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Jóhannesson, G.
    Johnson, R. P.
    Johnson, T. J.
    Johnson, W. N.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knödlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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.
    Rainò, 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.
    Saz Parkinson, P. M.
    Sbarra, C.
    Scargle, J. D.
    Sgrò, 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, Z.
    Zimmer, S.
    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, p. 4-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 γ-ray telescope, covering the energy range from 20MeV to more than 300GeV. 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.

  • 29. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, W. N.
    Kamae, T.
    Kawano, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle 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, Z.
    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, p. 15-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.

  • 30. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Kawano, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, p. 151103-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.

  • 31. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Kerr, M.
    Knodlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, Z.
    Zimmer, S.
    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, p. 4-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.

  • 32. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, R. P.
    Johnson, A. S.
    Kamae, T.
    Kataoka, J.
    Kerr, M.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, Z.
    Zimmer, S.
    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, p. 54-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.

  • 33. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Katagiri, H.
    Kataoka, J.
    Knodlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, Z.
    Zimmer, S.
    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, p. 22-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.

  • 34. 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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Kataoka, J.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    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, p. 1190-1192Article 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.

  • 35. Ackermann, M.
    et al.
    Ajello, M.
    Asano, K.
    Axelsson, Magnus
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    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, J.
    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, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    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, S.
    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, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Morselli, A.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Nymark, Tanja
    KTH, School of Engineering Sciences (SCI), Physics.
    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, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    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, Z.
    The first Fermi-Lat gamma-ray burst catalog2013In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 209, no 1, p. 11-Article 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.

  • 36. Ackermann, M.
    et al.
    Ajello, M.
    Asano, K.
    Baldini, L.
    Barbiellini, G.
    Baring, M. G.
    Bastieri, D.
    Bellazzini, R.
    Blandford, R. D.
    Bonamente, E.
    Borgland, A. W.
    Bottacini, E.
    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.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Conrad, J.
    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.
    Favuzzi, C.
    Fegan, S. J.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Gehrels, N.
    Giglietto, N.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Granot, J.
    Greiner, J.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hanabata, Y.
    Hayashida, M.
    Hays, E.
    Hughes, R. E.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Jóhannesson, G.
    Johnson, A. S.
    Knödlseder, J.
    Kocevski, D.
    Kuss, M.
    Lande, J.
    Larsson, S.
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    McEnery, J. E.
    Mehault, J.
    Mészáros, P.
    Michelson, P. F.
    Mitthumsiri, W.
    Mizuno, T.
    Monte, C.
    Monzani, M. E.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Naumann-Godo, M.
    Norris, J. P.
    Nuss, E.
    Nymark, Tanja
    KTH, School of Engineering Sciences (SCI), Physics.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Paneque, D.
    Perkins, J. S.
    Pesce-Rollins, M.
    Piron, F.
    Pivato, G.
    Racusin, J. L.
    Rainò, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Romoli, C.
    Roth, M.
    Ryde, Felix
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Sanchez, D. A.
    Sgrò, C.
    Siskind, E. J.
    Sonbas, E.
    Spinelli, P.
    Stamatikos, M.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Winer, B. L.
    Wood, K. S.
    Yang, Z.
    Gruber, D.
    Bhat, P. N.
    Bissaldi, E.
    Briggs, M. S.
    Burgess, J. M.
    Connaughton, V.
    Foley, S.
    Kippen, R. M.
    Kouveliotou, C.
    McBreen, S.
    McGlynn, S.
    Paciesas, W. S.
    Pelassa, V.
    Preece, R.
    Rau, A.
    Van Der Horst, A. J.
    Von Kienlin, A.
    Kann, D. A.
    Filgas, R.
    Klose, S.
    Krühler, T.
    Fukui, A.
    Sako, T.
    Tristram, P. J.
    Oates, S. R.
    Ukwatta, T. N.
    Littlejohns, O.
    Multiwavelength observations of GRB 110731A: GeV emission from onset to afterglow2013In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 763, no 2, p. 71-Article in journal (Refereed)
    Abstract [en]

    We report on the multiwavelength observations of the bright, long gamma-ray burst GRB 110731A, by the Fermi and Swift observatories, and by the MOA and GROND optical telescopes. The analysis of the prompt phase reveals that GRB 110731A shares many features with bright Large Area Telescope bursts observed by Fermi during the first three years on-orbit: a light curve with short time variability across the whole energy range during the prompt phase, delayed onset of the emission above 100 MeV, extra power-law component and temporally extended high-energy emission. In addition, this is the first GRB for which simultaneous GeV, X-ray, and optical data are available over multiple epochs beginning just after the trigger time and extending for more than 800 s, allowing temporal and spectral analysis in different epochs that favor emission from the forward shock in a wind-type medium. The observed temporally extended GeV emission is most likely part of the high-energy end of the afterglow emission. Both the single-zone pair transparency constraint for the prompt signal and the spectral and temporal analysis of the forward-shock afterglow emission independently lead to an estimate of the bulk Lorentz factor of the jet Γ ∼ 500-550.

  • 37. Ackermann, M.
    et al.
    Ajello, M.
    Atwood, W. B.
    Baldini, L.
    Barbiellini, 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.
    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, J.
    Cuoco, A.
    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.
    Fegan, S. J.
    Focke, W. B.
    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.
    Guiriec, S.
    Gustafsson, M.
    Hadasch, D.
    Hayashida, M.
    Horan, D.
    Hughes, R. E.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Kamae, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Latronico, L.
    Lionetto, A. M.
    Garde, M. Llena
    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.
    Norris, J. P.
    Nuss, E.
    Ohsugi, T.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Pesce-Rollins, M.
    Pierbattista, M.
    Piron, F.
    Pivato, G.
    Poon, H.
    Raino, S.
    Rando, R.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Romoli, C.
    Sbarra, C.
    Scargle, J. D.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Stawarz, Lukasz
    Strong, A. W.
    Suson, D. J.
    Tajima, H.
    Takahashi, H.
    Tanaka, T.
    Thayer, J. G.
    Thayer, J. B.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Wallace, E.
    Wood, K. S.
    Wood, M.
    Yang, Z.
    Zaharijas, G.
    Zimmer, S.
    Constraints on the galactic halo dark matter from fermi-lat diffuse measurements2012In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 761, no 2, p. 91-Article in journal (Refereed)
    Abstract [en]

    We have performed an analysis of the diffuse gamma-ray emission with the Fermi Large Area Telescope (LAT) in the Milky Way halo region, searching for a signal from dark matter annihilation or decay. In the absence of a robust dark matter signal, constraints are presented. We consider both gamma rays produced directly in the dark matter annihilation/decay and produced by inverse Compton scattering of the e(+)/e(-) produced in the annihilation/decay. Conservative limits are derived requiring that the dark matter signal does not exceed the observed diffuse gamma-ray emission. A second set of more stringent limits is derived based on modeling the foreground astrophysical diffuse emission using the GALPROP code. Uncertainties in the height of the diffusive cosmic-ray halo, the distribution of the cosmic-ray sources in the Galaxy, the index of the injection cosmic-ray electron spectrum, and the column density of the interstellar gas are taken into account using a profile likelihood formalism, while the parameters governing the cosmic-ray propagation have been derived from fits to local cosmic-ray data. The resulting limits impact the range of particle masses over which dark matter thermal production in the early universe is possible, and challenge the interpretation of the PAMELA/Fermi-LAT cosmic ray anomalies as the annihilation of dark matter.

  • 38.
    Ackermann, M.
    et al.
    Deutsch Elektronen Synchrotron DESY.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Zimmer, S.
    et al.,
    Detection of the Characteristic Pion-Decay Signature in Supernova Remnants2013In: Science, ISSN 0036-8075, Vol. 339, no 6121Article 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.

  • 39. Ajello, M.
    et al.
    Albert, A.
    Allafort, A.
    Baldini, L.
    Barbiellini, G.
    Bastieri, D.
    Bellazzini, R.
    Bissaldi, E.
    Bonamente, E.
    Brandt, T. J.
    Bregeon, J.
    Brigida, M.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cecchi, C.
    Charles, E.
    Chekhtman, A.
    Chiang, J.
    Chiaro, G.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    Cominsky, L. R.
    Conrad, J.
    Cutini, S.
    D'Ammando, F.
    de Palma, F.
    Dermer, C. D.
    Desiante, R.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Horan, D.
    Hou, X.
    Hughes, R. E.
    Inoue, Y.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Johannesson, G.
    Johnson, A. S.
    Johnson, W. N.
    Kamae, T.
    Knoedlseder, J.
    Kocevski, D.
    Kuss, M.
    Lande, J.
    Larsson, S.
    Latronico, L.
    Longo, F.
    Loparco, F.
    Lott, B.
    Lovellette, M. N.
    Lubrano, P.
    Mayer, M.
    Mazziotta, M. N.
    McEnery, J. E.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Murphy, R.
    Nakamori, T.
    Nemmen, R.
    Nuss, E.
    Ohno, M.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Ormes, J. F.
    Paneque, D.
    Panetta, J. H.
    Perkins, J. S.
    Pesce-Rollins, M.
    Petrosian, V.
    Piron, F.
    Pivato, G.
    Porter, T. A.
    Raino, S.
    Rando, R.
    Razzano, M.
    Reimer, A.
    Reimer, O.
    Roth, M.
    Schulz, A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Takahashi, H.
    Thayer, J. G.
    Thayer, J. B.
    Thompson, D. J.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Werner, M.
    Winer, B. L.
    Wood, D. L.
    Wood, K. S.
    Yang, Z.
    Impulsive and long duration high-energy gamma-ray emission from the very bright 2012 march 7 solar flares2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 789, no 1, p. 20-Article in journal (Refereed)
    Abstract [en]

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

  • 40.
    Axelsson, Magnus
    et al.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jackson, Miranda
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Lundman, Christoffer
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Moretti, Elena
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Nymark, Tanja
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Pe'Er, A.
    et al.,
    GRB110721A: An extreme peak energy and signatures of the photosphere2012In: The Astrophysical Journal. Letters, ISSN 2041-8205, Vol. 757, no 2, p. L31-Article in journal (Refereed)
    Abstract [en]

    GRB110721A was observed by the Fermi Gamma-ray Space Telescope using its two instruments the Large Area Telescope (LAT) and the Gamma-ray Burst Monitor (GBM). The burst consisted of one major emission episode which lasted for ~24.5 seconds (in the GBM) and had a peak flux of 5.7\pm0.2 x 10^{-5} erg/s/cm^2. The time-resolved emission spectrum is best modeled with a combination of a Band function and a blackbody spectrum. The peak energy of the Band component was initially 15\pm2 MeV, which is the highest value ever detected in a GRB. This measurement was made possible by combining GBM/BGO data with LAT Low Energy Events to achieve continuous 10--100 MeV coverage. The peak energy later decreased as a power law in time with an index of -1.89\pm0.10. The temperature of the blackbody component also decreased, starting from ~80 keV, and the decay showed a significant break after ~2 seconds. The spectrum provides strong constraints on the standard synchrotron model, indicating that alternative mechanisms may give rise to the emission at these energies.

  • 41. Barbiellini, G.
    et al.
    Bastieri, D.
    Bechtol, K.
    Bellazzini, R.
    Blandford, R. D.
    Borgland, A. W.
    Bregeon, J.
    Bruel, P.
    Buehler, R.
    Buson, S.
    Caliandro, G. A.
    Cameron, R. A.
    Caraveo, P. A.
    Cavazzuti, E.
    Cecchi, C.
    Chaves, R. C. G.
    Chekhtman, A.
    Cheung, C. C.
    Chiang, J.
    Ciprini, S.
    Claus, R.
    Cohen-Tanugi, J.
    D'Ammando, F.
    de Angelis, A.
    Dermer, C. D.
    Digel, S. W.
    do Couto e Silva, E.
    Drell, P. S.
    Drlica-Wagner, A.
    Favuzzi, C.
    Focke, W. B.
    Franckowiak, A.
    Fukazawa, Y.
    Fusco, P.
    Gargano, F.
    Gasparrini, D.
    Germani, S.
    Giglietto, N.
    Giommi, P.
    Giordano, F.
    Giroletti, M.
    Glanzman, T.
    Godfrey, G.
    Grenier, I. A.
    Grove, J. E.
    Guiriec, S.
    Hadasch, D.
    Hayashida, M.
    Hays, E.
    Hughes, R. E.
    Jackson, Miranda S.
    KTH, School of Engineering Sciences (SCI), Physics, Particle and Astroparticle Physics.
    Jogler, T.
    Knoedlseder, J.
    Kuss, M.
    Lande, J.
    Larsson, S.
    Longo, F.
    Loparco, F.
    Lovellette, M. N.
    Lubrano, P.
    Mazziotta, M. N.
    Mehault, J.
    Michelson, P. F.
    Mizuno, T.
    Moiseev, A. A.
    Monte, C.
    Monzani, M. E.
    Morselli, A.
    Moskalenko, I. V.
    Murgia, S.
    Nemmen, R.
    Nuss, E.
    Ohsugi, T.
    Omodei, N.
    Orienti, M.
    Orlando, E.
    Paneque, D.
    Perkins, J. S.
    Piron, F.
    Pivato, G.
    Prokhorov, D.
    Raino, S.
    Razzano, M.
    Razzaque, S.
    Reimer, A.
    Reimer, O.
    Ritz, S.
    Romoli, C.
    Sanchez-Conde, M.
    Sanchez, D. A.
    Sgro, C.
    Siskind, E. J.
    Spandre, G.
    Spinelli, P.
    Takahashi, H.
    Tanaka, T.
    Tibaldo, L.
    Tinivella, M.
    Tosti, G.
    Troja, E.
    Usher, T. L.
    Vandenbroucke, J.
    Vasileiou, V.
    Vianello, G.
    Vitale, V.
    Waite, A. P.
    Winer, B. L.
    Wood, K. S.
    Yang, Z.
    Fermi large area telescope observations of blazar 3C 279 occultations by the sun2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 784, no 2, p. 118-Article in journal (Refereed)
    Abstract [en]

    Observations of occultations of bright. gamma-ray sources by the Sun may reveal predicted pair halos around blazars and/or new physics, such as, e.g., hypothetical light dark matter particles-axions. We use Fermi Gamma-Ray Space Telescope (Fermi) data to analyze four occultations of blazar 3C 279 by the Sun on October 8 each year from 2008 to 2011. A combined analysis of the observations of these occultations allows a point-like source at the position of 3C 279 to be detected with significance of approximate to 3 sigma, but does not reveal any significant excess over the flux expected from the quiescent Sun. The likelihood ratio test rules out complete transparency of the Sun to the blazar. gamma-ray emission at a 3s confidence level.

  • 42.