Resolving the Extragalactic $\gamma$-Ray Background above 50 GeV with the Fermi Large Area Telescope

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

doi:10.1103/PhysRevLett.116.151105

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$Resolving the Extragalactic $\gamma$-Ray Background above 50 GeV with the Fermi Large Area Telescope$

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Resolving the Extragalactic $\gamma$-Ray Background above 50 GeV with the Fermi Large Area Telescope

M. Ackermann, M. Ajello, A. Albert, W.B. Atwood, L. Baldini, J. Ballet, G. Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, …

Physical Review Letters, Vol.116(15)

2016

DOI: https://doi.org/10.1103/PhysRevLett.116.151105

Abstract

photon: fluctuation

flux: energy dependence

background

blazar: energy spectrum

Cherenkov Telescope Array

angular resolution

Monte Carlo

acceptance

Euclidean

gamma ray: emission

galaxy

GLAST

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 γ-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 (∼8×10-12 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 [8×10-12,1.5×10-11] ph cm-2 s-1 and power-law indices below and above the break of α2∈[1.60,1.75] and α1=2.49±0.12, respectively. Integration of dN/dS shows that point sources account for at least 86-14+16% of the total extragalactic γ-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.

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Title: Resolving the Extragalactic $\gamma$-Ray Background above 50 GeV with the Fermi Large Area Telescope
Creators - without role: M. Ackermann - Deutsches Elektronen-Synchrotron DESY
M. Ajello - Clemson University
A. Albert - Kavli Institute for Particle Astrophysics and Cosmology
W.B. Atwood - University of California, Santa Cruz
L. Baldini - Kavli Institute for Particle Astrophysics and Cosmology
J. Ballet - CEA Paris-Saclay
G. Barbiellini - University of Trieste
D. Bastieri - University of Padua
K. Bechtol - University of Wisconsin–Madison
R. Bellazzini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
E. Bissaldi - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
R.D. Blandford - Kavli Institute for Particle Astrophysics and Cosmology
E.D. Bloom - Kavli Institute for Particle Astrophysics and Cosmology
R. Bonino - University of Turin
J. Bregeon - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
R.J. Britto - University of Johannesburg
P. Bruel - Laboratoire Leprince-Ringuet
R. Buehler - Deutsches Elektronen-Synchrotron DESY
G.A. Caliandro - Kavli Institute for Particle Astrophysics and Cosmology
R.A. Cameron - Stanford University
M. Caragiulo - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
P.A. Caraveo - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
E. Cavazzuti - Agenzia Spaziale Italiana
C. Cecchi - University of Perugia
E. Charles - Kavli Institute for Particle Astrophysics and Cosmology
A. Chekhtman - George Mason University
J. Chiang - Kavli Institute for Particle Astrophysics and Cosmology
G. Chiaro - University of Padua
S. Ciprini - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
Johann Cohen-Tanugi - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
L.R. Cominsky - Sonoma State University
F. Costanza - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
S. Cutini - Istituto Nazionale di Fisica Nucleare, Sezione di Perugia
F. d'Ammando
A. de Angelis - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
F. de Palma - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
R. Desiante - Istituto Nazionale di Fisica Nucleare, Sezione di Torino
S.W. Digel - Stanford University
M. Di Mauro - Kavli Institute for Particle Astrophysics and Cosmology
L. Di Venere - Polytechnic University of Bari
A. Dominguez - Clemson University
P.S. Drell - Kavli Institute for Particle Astrophysics and Cosmology
C. Favuzzi - Polytechnic University of Bari
S.J. Fegan - Laboratoire Leprince-Ringuet
E.C. Ferrara - Goddard Space Flight Center
A. Franckowiak - Kavli Institute for Particle Astrophysics and Cosmology
Y. Fukazawa - Hiroshima University
S. Funk - Universitätsklinikum Erlangen
P. Fusco - Polytechnic University of Bari
F. Gargano - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
D. Gasparrini - Agenzia Spaziale Italiana
N. Giglietto - Polytechnic University of Bari
P. Giommi - Agenzia Spaziale Italiana
F. Giordano - Polytechnic University of Bari
M. Giroletti - Istituto di Radioastronomia di Bologna
G. Godfrey - Kavli Institute for Particle Astrophysics and Cosmology
D. Green - University of Maryland, College Park
I.A. Grenier - CEA Paris-Saclay
S. Guiriec - Goddard Space Flight Center
E. Hays - Goddard Space Flight Center
D. Horan - Laboratoire Leprince-Ringuet
G. Iafrate - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
T. Jogler - Stanford University
G. Johannesson - University of Iceland
M. Kuss - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
G. La Mura - University of Padua
S. Larsson - KTH Royal Institute of Technology
L. Latronico - Istituto Nazionale di Fisica Nucleare, Sezione di Torino
J. Li - Institute of Space Sciences
L. Li - AlbaNova
F. Longo - Istituto Nazionale di Fisica Nucleare, Sezione di Trieste
F. Loparco - Polytechnic University of Bari
B. Lott - Laboratoire de Physique des deux infinis Bordeaux
M.N. Lovellette - United States Naval Research Laboratory
P. Lubrano - University of Perugia
G.M. Madejski - Kavli Institute for Particle Astrophysics and Cosmology
J. Magill - University of Maryland, College Park
S. Maldera - Istituto Nazionale di Fisica Nucleare, Sezione di Torino
A. Manfreda - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
M. Mayer - Deutsches Elektronen-Synchrotron DESY
M.N. Mazziotta - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
P.F. Michelson - Kavli Institute for Particle Astrophysics and Cosmology
W. Mitthumsiri - Mahidol University
T. Mizuno - Hiroshima University
A.A. Moiseev - Goddard Space Flight Center
M.E. Monzani - Kavli Institute for Particle Astrophysics and Cosmology
A. Morselli - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
I.V. Moskalenko - Stanford University
S. Murgia - University of California, Irvine
M. Negro - Istituto Nazionale di Fisica Nucleare, Sezione di Torino
E. Nuss - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
T. Ohsugi - Hiroshima University
C. Okada - Hiroshima University
N. Omodei - Kavli Institute for Particle Astrophysics and Cosmology
E. Orlando - Kavli Institute for Particle Astrophysics and Cosmology
J.F. Ormes - University of Denver
D. Paneque - Max Planck Institute for Physics
J.S. Perkins - Goddard Space Flight Center
M. Pesce-Rollins - Stanford University
V. Petrosian - Stanford University
F. Piron - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
G. Pivato - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
T.A. Porter - Kavli Institute for Particle Astrophysics and Cosmology
S. Raino - Polytechnic University of Bari
R. Rando - University of Padua
M. Razzano - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
S. Razzaque - University of Johannesburg
A. Reimer - Universität Innsbruck
O. Reimer - Universität Innsbruck
T. Reposeur - Laboratoire de Physique des deux infinis Bordeaux
R.W. Romani - Kavli Institute for Particle Astrophysics and Cosmology
M. Sanchez-Conde - AlbaNova
J. Schmid - Université Paris Cité
A. Schulz - Deutsches Elektronen-Synchrotron DESY
C. Sgro - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
D. Simone - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
E.J. Siskind - Real Time Tomography
F. Spada - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
G. Spandre - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
P. Spinelli - Polytechnic University of Bari
D.J. Suson - Purdue University Northwest
H. Takahashi - Hiroshima University
J.B. Thayer - Stanford University
L. Tibaldo - Max Planck Institute for Nuclear Physics
D.F. Torres - Institució Catalana de Recerca i Estudis Avançats
E. Troja - University of Maryland, College Park
G. Vianello - Kavli Institute for Particle Astrophysics and Cosmology
M. Yassine - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
S. Zimmer - Stockholm University
Publication Details: Physical Review Letters, Vol.116(15)
Identifiers: 9944715909311
Academic Unit: Laboratoire Univers et Particules de Montpellier - LUPM
Language: English
Resource Type: Journal article
Local Fields: hal-01555001