Anisotropies in the diffuse gamma-ray background measured by the Fermi-LAT

Markus Ackermann; Marco Ajello; A. Albert; Luca Baldini; Jean Ballet; Guido Barbiellini; D. Bastieri; K. Bechtol; R. Bellazzini; E. D. Bloom; E. Bonamente; A.W. Borgland; T. J. Brandt; J. Bregeon; M. Brigida; Pascal Bruel; R. Buehler; S. Buson; G. A. Caliandro; R. A. Cameron; P. A. Caraveo; C. Cecchi; E. Charles; A. Chekhtman; J. Chiang; S. Ciprini; R. Claus; J. Cohen-Tanugi; J. Conrad; A. Cuoco; S. Cutini; F. d'Ammando; F. de Palma; C. D. Dermer; S.W. Digel; E. Do Couto E Silva; P. S. Drell; A. Drlica-Wagner; R. Dubois; C. Favuzzi; S. J. Fegan; E. C. Ferrara; P. Fortin; Y. Fukazawa; P. Fusco; F. Gargano; D. Gasparrini; S. Germani; N. Giglietto; M. Giroletti; T. Glanzman; G. Godfrey; G. Gomez-Vargas; T. Gre'Goire; I. A. Grenier; J. E. Grove; S. Guiriec; M. Gustafsson; D. Hadasch; M. Hayashida; K. Hayashi; X. Hou; R. E. Hughes; G. Jo'Hannesson; A. S. Johnson; T. Kamae; Jürgen Knödlseder; M. Kuss; J. Lande; L. Latronico; M. Lemoine-Goumard; T. Linden; A. M. Lionetto; M. Llena Garde; F. Longo; F. Loparco; M. N. Lovellette; P. Lubrano; M. N. Mazziotta; J. E. Mcenery; W. Mitthumsiri; T. Mizuno; C. Monte; M. E. Monzani; A. Morselli; I.V. Moskalenko; S. Murgia; M. Naumann-Godo; J. P. Norris; E. Nuss; T. Ohsugi; A. Okumura; M. Orienti; E. Orlando; J.F. Ormes; D. Paneque; J. H. Panetta; D. Parent; V. Pavlidou; M. Pesce-Rollins; M. Pierbattista; F. Piron; G. Pivato; S. Raino'; R. Rando; A. Reimer; O. Reimer; M. Roth; C. Sbarra; J. Schmitt; C. Sgro'; J. Siegal-Gaskins; E. J. Siskind; G. Spandre; P. Spinelli; A.W. Strong; D. J. Suson; H. Takahashi; T. Tanaka; J. B. Thayer; L. Tibaldo; M. Tinivella; D. F. Torres; G. Tosti; E. Troja; T. L. Usher; J. Vandenbroucke; V. Vasileiou; G. Vianello; V. Vitale; A. P. Waite; B. L. Winer; K. S. Wood; M. Wood; Z. Yang; S. Zimmer

doi:10.1103/PhysRevD.85.083007

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Anisotropies in the diffuse gamma-ray background measured by the Fermi-LAT

Markus Ackermann, Marco Ajello, A. Albert, Luca Baldini, Jean Ballet, Guido Barbiellini, D. Bastieri, K. Bechtol, R. Bellazzini, E. D. Bloom, …

Physical Review D, Vol.85

2012

DOI: https://doi.org/10.1103/PhysRevD.85.083007

Abstract

The contribution of unresolved sources to the diffuse gamma-ray background could induce anisotropies in this emission on small angular scales. We analyze the angular power spectrum of the diffuse emission measured by the Fermi LAT at Galactic latitudes |b| > 30 deg in four energy bins spanning 1 to 50 GeV. At multipoles \ell \ge 155, corresponding to angular scales \lesssim 2 deg, angular power above the photon noise level is detected at >99.99% CL in the 1-2 GeV, 2-5 GeV, and 5-10 GeV energy bins, and at >99% CL at 10-50 GeV. Within each energy bin the measured angular power takes approximately the same value at all multipoles \ell \ge 155, suggesting that it originates from the contribution of one or more unclustered source populations. The amplitude of the angular power normalized to the mean intensity in each energy bin is consistent with a constant value at all energies, C_P/<I>^2 = 9.05 +/- 0.84 x 10^{-6} sr, while the energy dependence of C_P is consistent with the anisotropy arising from one or more source populations with power-law photon spectra with spectral index \Gamma_s = 2.40 +/- 0.07. We discuss the implications of the measured angular power for gamma-ray source populations that may provide a contribution to the diffuse gamma-ray background.

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Title: Anisotropies in the diffuse gamma-ray background measured by the Fermi-LAT
Creators - without role: Markus Ackermann - Istituto Nazionale di Fisica Nucleare
Marco Ajello - Istituto Nazionale di Fisica Nucleare
A. Albert - The Ohio State University
Luca Baldini - Albert Einstein College of Medicine
Jean Ballet - California Institute of Technology
Guido Barbiellini - Albert Einstein College of Medicine
D. Bastieri - University of California, Santa Cruz
K. Bechtol - The University of Texas at Austin
R. Bellazzini - Istituto Nazionale di Fisica Nucleare, Sezione di Pisa
E. D. Bloom
E. Bonamente - The University of Texas at Austin
A.W. Borgland - Stanford University
T. J. Brandt - Institut de Recherche en Astrophysique et Planétologie
J. Bregeon - Albert Einstein College of Medicine
M. Brigida - The University of Texas at Austin
Pascal Bruel - Centre National de la Recherche Scientifique
R. Buehler - Kavli Institute for Particle Astrophysics and Cosmology
S. Buson - The University of Texas at Austin
G. A. Caliandro
R. A. Cameron
P. A. Caraveo - Istituto di Astrofisica Spaziale e Fisica Cosmica di Milano
C. Cecchi - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
E. Charles - The University of Texas at Austin
A. Chekhtman - George Mason University
J. Chiang - California Institute of Technology
S. Ciprini - The University of Texas at Austin
R. Claus - Kavli Institute for Particle Astrophysics and Cosmology
J. Cohen-Tanugi - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
J. Conrad - Albert Einstein College of Medicine
A. Cuoco - AlbaNova
S. Cutini - The University of Texas at Austin
F. d'Ammando
F. de Palma - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
C. D. Dermer
S.W. Digel - Kavli Institute for Particle Astrophysics and Cosmology
E. Do Couto E Silva
P. S. Drell
A. Drlica-Wagner - Kavli Institute for Particle Astrophysics and Cosmology
R. Dubois - SLAC National Accelerator Laboratory
C. Favuzzi - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
S. J. Fegan - Laboratoire Leprince-Ringuet
E. C. Ferrara
P. Fortin - Centre National de la Recherche Scientifique
Y. Fukazawa - Hiroshima University
P. Fusco - Polytechnic University of Bari
F. Gargano - Istituto Nazionale di Fisica Nucleare, Sezione di Bari
D. Gasparrini - University of California, Santa Cruz
S. Germani - The University of Texas at Austin
N. Giglietto - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
M. Giroletti - The University of Texas at Austin
T. Glanzman - The University of Texas at Austin
G. Godfrey - California Institute of Technology
G. Gomez-Vargas - California Institute of Technology
T. Gre'Goire
I. A. Grenier - Astrophysique Interprétation Modélisation
J. E. Grove
S. Guiriec - The University of Texas at Austin
M. Gustafsson - The University of Texas at Austin
D. Hadasch - University of California, Santa Cruz
M. Hayashida - The University of Texas at Austin
K. Hayashi - The University of Texas at Austin
X. Hou - Laboratoire de Physique des deux infinis Bordeaux
R. E. Hughes
G. Jo'Hannesson
A. S. Johnson
T. Kamae - The University of Texas at Austin
Jürgen Knödlseder - California Institute of Technology
M. Kuss - The University of Texas at Austin
J. Lande - Albert Einstein College of Medicine
L. Latronico - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
M. Lemoine-Goumard - The University of Texas at Austin
T. Linden - University of California, Santa Cruz
A. M. Lionetto
M. Llena Garde
F. Longo - Fermi National Accelerator Laboratory
F. Loparco - Polytechnic University of Bari
M. N. Lovellette
P. Lubrano - University of Perugia
M. N. Mazziotta
J. E. Mcenery
W. Mitthumsiri - Fermi National Accelerator Laboratory
T. Mizuno - The University of Texas at Austin
C. Monte - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
M. E. Monzani
A. Morselli - The University of Texas at Austin
I.V. Moskalenko - Universidad Autónoma de Madrid
S. Murgia - The University of Texas at Austin
M. Naumann-Godo - The University of Texas at Austin
J. P. Norris
E. Nuss - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
T. Ohsugi - The University of Texas at Austin
A. Okumura - Institute of Space and Astronautical Science
M. Orienti - The University of Texas at Austin
E. Orlando - The University of Texas at Austin
J.F. Ormes - University of Denver
D. Paneque - University of California, Santa Cruz
J. H. Panetta
D. Parent - University of California, Santa Cruz
V. Pavlidou - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
M. Pesce-Rollins - The University of Texas at Austin
M. Pierbattista - The University of Texas at Austin
F. Piron - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
G. Pivato - California Institute of Technology
S. Raino'
R. Rando - Universidad Autónoma de Madrid
A. Reimer - Universität Innsbruck
O. Reimer - The University of Texas at Austin
M. Roth - The University of Texas at Austin
C. Sbarra - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
J. Schmitt - Astrophysique Interprétation Modélisation
C. Sgro'
J. Siegal-Gaskins - California Institute of Technology
E. J. Siskind
G. Spandre - California Institute of Technology
P. Spinelli - The University of Texas at Austin
A.W. Strong - Fermi National Accelerator Laboratory
D. J. Suson
H. Takahashi - The University of Texas at Austin
T. Tanaka - The University of Texas at Austin
J. B. Thayer
L. Tibaldo - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
M. Tinivella - The University of Texas at Austin
D. F. Torres
G. Tosti - California Institute of Technology
E. Troja - The University of Texas at Austin
T. L. Usher
J. Vandenbroucke - California Institute of Technology
V. Vasileiou - Université de Montpellier, Laboratoire Univers et Particules de Montpellier - LUPM
G. Vianello - California Institute of Technology
V. Vitale - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
A. P. Waite
B. L. Winer
K. S. Wood
M. Wood - The University of Texas at Austin
Z. Yang - Istituto Nazionale di Fisica Nucleare, Roma Tor Vergata
S. Zimmer - The University of Texas at Austin
Publication Details: Physical Review D, Vol.85
Identifiers: 9938679909311
Academic Unit: Laboratoire Univers et Particules de Montpellier - LUPM
Language: English
Resource Type: Journal article
Local Fields: in2p3-00699970