Resolving the extragalactic γ-ray background above 50 GeV with the fermi large area telescope

Reposeur T, Di Mauro M, Zimmer S, Negro M, La Mura G, Sanchez-Conde M, Britto RJ, Cavazzuti E, Bonino R, Iafrate G, Moskalenko IV, Orlando E, Porter TA, Reimer A, Reimer O, Dominguez A, Lott B, Simone D, Buehler R, Caragiulo M, Caraveo PA, Spada F, Cecchi C, Magill J, Chekhtman A, Mitthumsiri W, Godfrey G, Jogler T, Tibaldo L, Franckowiak A, Costanza F, Drell PS, Di Venere L, Monzani ME, D'Ammando F, Maldera S, Michelson PF, Ciprini S, Spinelli P, Bissaldi E, Horan D, Funk S, Ferrara EC, Chiaro G, Fukazawa Y, Piron F, Johannesson G, Ackermann M, Bruel P, Caliandro GA, Cameron RA, Charles E, Chiang J, Grenier IA, Schmid J, Albert A, Bloom ED, Pesce-Rollins M, Gargano F, Madejski GM, Gasparrini D, Digel SW, Yassine M, Pivato G, Hays E, Giroletti M, Desiante R, De Palma F, Guiriec S, Favuzzi C, Troja E, Torres DF, Schulz A, Atwood WB, Takahashi H, Suson DJ, Li J, Morselli A, Paneque D, Romani RW, Ajello M, Cutini S, Ballet J, Perkins JS, Giommi P, Razzano M, Nuss E, Rando R, Razzaque S, Okada C, Siskind EJ, Fegan SJ, Sgro C, Bechtol K, Cominsky LR, Li L, Larsson S, Vianello G, Cohen-Tanugi J, Thayer JB, Bellazzini R, Bastieri D, Barbiellini G, Moiseev AA, Mizuno T, Mazziotta MN, Mayer M, De Angelis A, Ormes JF, Ohsugi T, Murgia S, Bregeon J, Omodei N, Blandford RD, Petrosian V, Spandre G, Kuss M, Lubrano P, Baldini L, Longo F, Latronico L, Lovellette MN, Raino S, Green D, Manfreda A, Giglietto N, Fusco P, Loparco F, Giordano F (2016)

Publication Status: Published

Publication Type: Journal article, Original article

Publication year: 2016

Journal

Publisher: American Physical Society

Book Volume: 116

Article Number: 151105

Journal Issue: 15

DOI: 10.1103/PhysRevLett.116.151105

Abstract

The Fermi Large Area Telescope (LAT) Collaboration has recently released a catalog of 360 sources detected above 50 GeV (2FHL). This catalog was obtained using 80 months of data re-processed with Pass 8, the newest event-level analysis, which significantly improves the acceptance and angular resolution of the instrument. Most of the 2FHL sources at high Galactic latitude are blazars. Using detailed Monte Carlo simulations, we measure, for the first time, the source count distribution, dN= dS, of extragalactic.-ray sources at E > 50 GeV and find that it is compatible with a Euclidean distribution down to the lowest measured source flux in the 2FHL (8 x 10(-12) ph cm(-2) s(-1)). We employ a one-point photon fluctuation analysis to constrain the behavior of dN= dS below the source detection threshold. Overall, the source count distribution is constrained over three decades in flux and found compatible with a broken power law with a break flux, Sb, in the range [8 x 10-12; 1.5 x 10-11] ph cm(-2) s(-1) and power-law indices below and above the break of a 2. [1.60; 1.75] and a 1 +/- 2.49 +/- 0.12, respectively. Integration of dN= dS shows that point sources account for at least 86_16 -14 % of the total extragalactic gamma-ray background. The simple form of the derived source count distribution is consistent with a single population (i. e., blazars) dominating the source counts to the minimum flux explored by this analysis. We estimate the density of sources detectable in blind surveys that will be performed in the coming years by the Cherenkov Telescope Array.

Authors with CRIS profile

Involved external institutions

Université Bordeaux 1, Sciences et Technologies France (FR) Stanford University United States (USA) (US) AlbaNova University Centre / Kungliga Tekniska Högskolan AlbaNova Universitetscentrum Sweden (SE) National Institute for Nuclear Physics / Istituto Nazionale di Fisica Nucleare (INFN) Italy (IT) University of Padua / Universita degli Studi di Padova Italy (IT) University of Johannesburg South Africa (ZA) Italian Space Agency / Agenzia Spaziale Italiana (ASI) Italy (IT) Clemson University United States (USA) (US) Deutsches Elektronen-Synchrotron DESY Germany (DE) National Institute for Astrophysics / Istituto Nazionale Astrofisica (INAF) Italy (IT) University of Maryland United States (USA) (US) George Mason University United States (USA) (US) Mahidol University / มหาวิทยาลัยมหิดล Thailand (TH) Max-Planck-Institut für Kernphysik (MPIK) / Max Planck Institute for Nuclear Physics Germany (DE) Institut national de physique nucléaire et de physique des particules (IN2P3) France (FR) National Aeronautics and Space Administration (NASA) United States (USA) (US) Hiroshima University / 広島大学 Japan (JP) University of Montpellier / Université Montpellier France (FR) University of Iceland (UI) / Háskóli Íslands Iceland (IS) University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot France (FR) Spanish National Research Council / Consejo Superior de Investigaciones Científicas (CSIC) Spain (ES) University of California Santa Cruz United States (USA) (US) Purdue University Northwest / Purdue University Calumet United States (USA) (US) NYCB Real-Time Computing, Inc. United States (USA) (US) University of Wisconsin - Madison United States (USA) (US) Sonoma State University United States (USA) (US) Royal Institute of Technology / Kungliga Tekniska Högskolan (KTH) Sweden (SE) University of Udine / Università degli Studi di Udine Italy (IT) University of Denver United States (USA) (US) University of California Irvine United States (USA) (US) U.S. Naval Research Laboratory United States (USA) (US)

How to cite

APA:

Reposeur, T., Di Mauro, M., Zimmer, S., Negro, M., La Mura, G., Sanchez-Conde, M.,... Giordano, F. (2016). Resolving the extragalactic γ-ray background above 50 GeV with the fermi large area telescope. Physical Review Letters, 116(15). https://doi.org/10.1103/PhysRevLett.116.151105

MLA:

Reposeur, T., et al. "Resolving the extragalactic γ-ray background above 50 GeV with the fermi large area telescope." Physical Review Letters 116.15 (2016).

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