Data di Pubblicazione:
2015
Abstract:
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 (DGE), and a longer data accumulation of 50 months allow for a refinement
and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to
820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature and can be well described over
nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 ± 0.02 and
a break energy of (279 ± 52) GeV using our baseline DGE model. The total intensity attributed to the IGRB is
(7.2 ± 0.6) × 10−6 cm−2 s−1 sr−1 above 100 MeV, with an additional +15%/−30% systematic uncertainty due to
the Galactic diffuse foregrounds.
Tipologia CRIS:
03A-Articolo su Rivista
Keywords:
diffuse radiation , gamma rays: diffuse background
Elenco autori:
Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W.B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Bissaldi, E.; Blandford, R.D.; Bloom, E.D.; Bottacini, E.; Brandt, T.J.; Bregeon, J.; Bruel, P.; Buehler, R.; Buson, S.; Caliandro, G.A.; Cameron, R.A.; Caragiulo, M.; Caraveo, P.A.; Cavazzuti, E.; Cecchi, C.; Charles, E.; Chekhtman, A.; Chiang, J.; Chiaro, G.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Conrad, J.; Cuoco, A.; Cutini, S.; D'Ammando, F.; De Angelis, A.; De Palma, F.; Dermer, C.D.; Digel, S.W.; Do Couto E Silva, E.; Drell, P.S.; Favuzzi, C.; Ferrara, E.C.; Focke, W.B.; Franckowiak, A.; Fukazawa, Y.; Funk, S.; Fusco, P.; Gargano, F.; Gasparrini, D.; Germani, S.; Giglietto, N.; Giommi, P.; Giordano, F.; Giroletti, M.; Godfrey, G.; Gomez-Vargas, G.A.; Grenier, I.A.; Guiriec, S.; Gustafsson, M.; Hadasch, D.; Hayashi, K.; Hays, E.; Hewitt, J.W.; Ippoliti, P.; Jogler, T.; Jóhannesson, G.; Johnson, A.S.; Johnson, W.N.; Kamae, T.; Kataoka, J.; Knödlseder, J.; Kuss, M.; Larsson, S.; Latronico, L.; Li, J.; Li, L.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M.N.; Lubrano, P.; Madejski, G.M.; Manfreda, A.; Massaro, F.; Mayer, M.; Mazziotta, M.N.; Mcenery, J.E.; Michelson, P.F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A.A.; Monzani, M.E.; Morselli, A.; Moskalenko, I.V.; Murgia, S.; Nemmen, R.; Nuss, E.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J.F.; Paneque, D.; Panetta, J.H.; Perkins, J.S.; Pesce-Rollins, M.; Piron, F.; Pivato, G.; Porter, T.A.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Reimer, O.; Reposeur, T.; Ritz, S.; Romani, R.W.; Sánchez-Conde, M.; Schaal, M.; Schulz, A.; Sgrò, C.; Siskind, E.J.; Spandre, G.; Spinelli, P.; Strong, A.W.; Suson, D.J.; Takahashi, H.; Thayer, J.G.; Thayer, J.B.; Tibaldo, L.; Tinivella, M.; Torres, D.F.; Tosti, G.; Troja, E.; Uchiyama, Y.; Vianello, G.; Werner, M.; Winer, B.L.; Wood, K.S.; Wood, M.; Zaharijas, G.; Zimmer, S.
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