The spectrum of isotropic diffuse gamma-ray emission between 100 MeV and 820 GeV
Creators: name: The Fermi LAT Collaboration
name: Ackermann, M.
name: Ajello, M.
name: Albert, A.
name: Atwood, W. B.
name: Baldini, L.
name: Ballet, J.
name: Barbiellini, G.
name: Bastieri, D.
name: Bechtol, K.
name: Bellazzini, R.
name: Bissaldi, E.
name: Blandford, R. D.
name: Bloom, E. D.
name: Bottacini, E.
name: Brandt, T. J.
name: Bregeon, J.
name: Bruel, P.
name: Buehler, R.
name: Buson, S.
name: Caliandro, G. A.
name: Cameron, R. A.
name: Caragiulo, M.
name: Caraveo, P. A.
name: Cavazzuti, E.
name: Cecchi, C.
name: Charles, E.
name: Chekhtman, A.
name: Chiang, J.
name: Chiaro, G.
name: Ciprini, S.
name: Claus, R.
name: Cohen-Tanugi, J.
name: Conrad, J.
name: Cuoco, A.
name: Cutini, S.
name: D'Ammando, F.
name: de Angelis, A.
name: de Palma, F.
name: Dermer, C. D.
name: Digel, S. W.
name: Silva, E. do Couto e
name: Drell, P. S.
name: Favuzzi, C.
name: Ferrara, E. C.
name: Focke, W. B.
name: Franckowiak, A.
name: Fukazawa, Y.
name: Funk, S.
name: Fusco, P.
name: Gargano, F.
name: Gasparrini, D.
name: Germani, S.
name: Giglietto, N.
name: Giommi, P.
name: Giordano, F.
name: Giroletti, M.
name: Godfrey, G.
name: Gomez-Vargas, G. A.
name: Grenier, I. A.
name: Guiriec, S.
name: Gustafsson, M.
name: Hadasch, D.
name: Hayashi, K.
name: Hays, E.
name: Hewitt, J. W.
name: Ippoliti, P.
name: Jogler, T.
name: Jóhannesson, G.
name: Johnson, A. S.
name: Johnson, W. N.
name: Kamae, T.
name: Kataoka, J.
name: Knödlseder, J.
name: Kuss, M.
name: Larsson, S.
name: Latronico, L.
name: Li, J.
name: Li, L.
name: Longo, F.
name: Loparco, F.
name: Lott, B.
name: Lovellette, M. N.
name: Lubrano, P.
name: Madejski, G. M.
name: Manfreda, A.
name: Massaro, F.
name: Mayer, M.
name: Mazziotta, M. N.
name: McEnery, J. E.
name: Michelson, P. F.
name: Mitthumsiri, W.
name: Mizuno, T.
name: Moiseev, A. A.
name: Monzani, M. E.
name: Morselli, A.
name: Moskalenko, I. V.
name: Murgia, S.
name: Nemmen, R.
name: Nuss, E.
name: Ohsugi, T.
name: Omodei, N.
name: Orlando, E.
name: Ormes, J. F.
name: Paneque, D.
name: Panetta, J. H.
name: Perkins, J. S.
name: Pesce-Rollins, M.
name: Piron, F.
name: Pivato, G.
name: Porter, T. A.
name: Rainò, S.
name: Rando, R.
name: Razzano, M.
name: Razzaque, S.
name: Reimer, A.
name: Reimer, O.
name: Reposeur, T.
name: Ritz, S.
name: Romani, R. W.
name: Sánchez-Conde, M.
name: Schaal, M.
name: Schulz, A.
name: Sgrò, C.
name: Siskind, E. J.
name: Spandre, G.
name: Spinelli, P.
name: Strong, A. W.
name: Suson, D. J.
name: Takahashi, H.
name: Thayer, J. G.
name: Thayer, J. B.
name: Tibaldo, L.
name: Tinivella, M.
name: Torres, D. F.
name: Tosti, G.
name: Troja, E.
name: Uchiyama, Y.
name: Vianello, G.
name: Werner, M.
name: Winer, B. L.
name: Wood, K. S.
name: Wood, M.
name: Zaharijas, G.
name: Zimmer, S.
Publisher: name: arXiv
Year: 2014
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: The γ-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse γ-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission, and a longer data accumulation of 50 months, allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature, and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of $2.32\pm0.02$ and a break energy of $(279\pm52)$ GeV using our baseline diffuse Galactic emission model. The total intensity attributed to the IGRB is $(7.2\pm0.6) \times 10^{-6}$ cm$^{-2}$ s$^{-1}$ sr$^{-1}$ above 100 MeV, with an additional $+15$%/$-30$% systematic uncertainty due to the Galactic diffuse foregrounds.
description: Accepted by The Astrophysical Journal