Spectrum of the isotropic diffuse gamma-ray emission derived from first-year Fermi Large Area Telescope data

A A Abdo; M Ackermann; M Ajello; W B Atwood; L Baldini; J Ballet; G Barbiellini; D Bastieri; B M Baughman; K Bechtol; R Bellazzini; B Berenji; R D Blandford; E D Bloom; E Bonamente; A W Borgland; J Bregeon; A Brez; M Brigida; P Bruel; T H Burnett; S Buson; G A Caliandro; R A Cameron; P A Caraveo; J M Casandjian; E Cavazzuti; C Cecchi; O Celik; E Charles; A Chekhtman; C C Cheung; J Chiang; S Ciprini; R Claus; J Cohen-Tanugi; L R Cominsky; J Conrad; S Cutini; C D Dermer; A de Angelis; F de Palma; S W Digel; G Di Bernardo; E do Couto e Silva; P S Drell; A Drlica-Wagner; R Dubois; D Dumora; C Farnier; C Favuzzi; S J Fegan; W B Focke; P Fortin; M Frailis; Y Fukazawa; S Funk; P Fusco; D Gaggero; F Gargano; D Gasparrini; N Gehrels; S Germani; B Giebels; N Giglietto; P Giommi; F Giordano; T Glanzman; G Godfrey; I A Grenier; M-H Grondin; J E Grove; L Guillemot; S Guiriec; M Gustafsson; Y Hanabata; A K Harding; M Hayashida; R E Hughes; R Itoh; M S Jackson; G Jóhannesson; A S Johnson; R P Johnson; T J Johnson; W N Johnson; T Kamae; H Katagiri; J Kataoka; N Kawai; M Kerr; J Knödlseder; M L Kocian; F Kuehn; M Kuss; J Lande; L Latronico; M Lemoine-Goumard; F Longo; F Loparco; B Lott; M N Lovellette; P Lubrano; G M Madejski; A Makeev; M N Mazziotta; W McConville; J E McEnery; C Meurer; P F Michelson; W Mitthumsiri; T Mizuno; A A Moiseev; C Monte; M E Monzani; A Morselli; I V Moskalenko; S Murgia; P L Nolan; J P Norris; E Nuss; T Ohsugi; N Omodei; E Orlando; J F Ormes; D Paneque; J H Panetta; D Parent; V Pelassa; M Pepe; M Pesce-Rollins; F Piron; T A Porter; S Rainò; R Rando; M Razzano; A Reimer; O Reimer; T Reposeur; S Ritz; L S Rochester; A Y Rodriguez; M Roth; F Ryde; H F-W Sadrozinski; D Sanchez; A Sander; P M Saz Parkinson; J D Scargle; A Sellerholm; C Sgrò; M S Shaw; E J Siskind; D A Smith; P D Smith; G Spandre; P Spinelli; J-L Starck; M S Strickman; A W Strong; D J Suson; H Tajima; H Takahashi; T Takahashi; T Tanaka; J B Thayer; J G Thayer; D J Thompson; L Tibaldo; D F Torres; G Tosti; A Tramacere; Y Uchiyama; T L Usher; V Vasileiou; N Vilchez; V Vitale; A P Waite; P Wang; B L Winer; K S Wood; T Ylinen; M Ziegler; Fermi LAT Collaboration

doi:10.1103/PhysRevLett.104.101101

Spectrum of the isotropic diffuse gamma-ray emission derived from first-year Fermi Large Area Telescope data

Phys Rev Lett. 2010 Mar 12;104(10):101101. doi: 10.1103/PhysRevLett.104.101101. Epub 2010 Mar 8.

Authors

A A Abdo¹, M Ackermann, M Ajello, W B Atwood, L Baldini, J Ballet, G Barbiellini, D Bastieri, B M Baughman, K Bechtol, R Bellazzini, B Berenji, R D Blandford, E D Bloom, E Bonamente, A W Borgland, J Bregeon, A Brez, M Brigida, P Bruel, T H Burnett, S Buson, G A Caliandro, R A Cameron, P A Caraveo, J M Casandjian, E Cavazzuti, C Cecchi, O Celik, E Charles, A Chekhtman, C C Cheung, J Chiang, S Ciprini, R Claus, J Cohen-Tanugi, L R Cominsky, J Conrad, S Cutini, C D Dermer, A de Angelis, F de Palma, S W Digel, G Di Bernardo, E do Couto e Silva, P S Drell, A Drlica-Wagner, R Dubois, D Dumora, C Farnier, C Favuzzi, S J Fegan, W B Focke, P Fortin, M Frailis, Y Fukazawa, S Funk, P Fusco, D Gaggero, F Gargano, D Gasparrini, N Gehrels, S Germani, B Giebels, N Giglietto, P Giommi, F Giordano, T Glanzman, G Godfrey, I A Grenier, M-H Grondin, J E Grove, L Guillemot, S Guiriec, M Gustafsson, Y Hanabata, A K Harding, M Hayashida, R E Hughes, R Itoh, M S Jackson, G Jóhannesson, A S Johnson, R P Johnson, T J Johnson, W N Johnson, T Kamae, H Katagiri, J Kataoka, N Kawai, M Kerr, J Knödlseder, M L Kocian, F Kuehn, M Kuss, J Lande, L Latronico, M Lemoine-Goumard, F Longo, F Loparco, B Lott, M N Lovellette, P Lubrano, G M Madejski, A Makeev, M N Mazziotta, W McConville, J E McEnery, C Meurer, P F Michelson, W Mitthumsiri, T Mizuno, A A Moiseev, C Monte, M E Monzani, A Morselli, I V Moskalenko, S Murgia, P L Nolan, J P Norris, E Nuss, T Ohsugi, N Omodei, E Orlando, J F Ormes, D Paneque, J H Panetta, D Parent, V Pelassa, M Pepe, M Pesce-Rollins, F Piron, T A Porter, S Rainò, R Rando, M Razzano, A Reimer, O Reimer, T Reposeur, S Ritz, L S Rochester, A Y Rodriguez, M Roth, F Ryde, H F-W Sadrozinski, D Sanchez, A Sander, P M Saz Parkinson, J D Scargle, A Sellerholm, C Sgrò, M S Shaw, E J Siskind, D A Smith, P D Smith, G Spandre, P Spinelli, J-L Starck, M S Strickman, A W Strong, D J Suson, H Tajima, H Takahashi, T Takahashi, T Tanaka, J B Thayer, J G Thayer, D J Thompson, L Tibaldo, D F Torres, G Tosti, A Tramacere, Y Uchiyama, T L Usher, V Vasileiou, N Vilchez, V Vitale, A P Waite, P Wang, B L Winer, K S Wood, T Ylinen, M Ziegler; Fermi LAT Collaboration

Affiliation

¹ Space Science Division, Naval Research Laboratory, Washington, D.C. 20375, USA.

PMID: 20366411
DOI: 10.1103/PhysRevLett.104.101101

Abstract

We report on the first Fermi Large Area Telescope (LAT) measurements of the so-called "extragalactic" diffuse gamma-ray emission (EGB). This component of the diffuse gamma-ray emission is generally considered to have an isotropic or nearly isotropic distribution on the sky with diverse contributions discussed in the literature. The derivation of the EGB is based on detailed modeling of the bright foreground diffuse Galactic gamma-ray emission, the detected LAT sources, and the solar gamma-ray emission. We find the spectrum of the EGB is consistent with a power law with a differential spectral index gamma = 2.41 +/- 0.05 and intensity I(>100 MeV) = (1.03 +/- 0.17) x 10(-5) cm(-2) s(-1) sr(-1), where the error is systematics dominated. Our EGB spectrum is featureless, less intense, and softer than that derived from EGRET data.