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

Journal article
(Original article)

Publication Details

Author(s): 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
Journal: Physical Review Letters
Publisher: American Physical Society
Publication year: 2016
Volume: 116
Journal issue: 15
ISSN: 0031-9007


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.

FAU Authors / FAU Editors

Funk, Stefan Prof. Dr.
Lehrstuhl für Physik

External institutions with authors

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

How to cite

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).

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).


Last updated on 2018-20-11 at 20:50