skip to main content
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: The Fermi -Lat High-Latitude Survey: Source Count Distributions And The Origin Of The Extragalactic Diffuse Background

Abstract

This is the first of a series of papers aimed at characterizing the populations detected in the high-latitude sky of the Fermi-LAT survey. In this work, we focus on the intrinsic spectral and flux properties of the source sample. We show that when selection effects are properly taken into account, Fermi sources are on average steeper than previously found (e.g., in the bright source list) with an average photon index of 2.40 ± 0.02 over the entire 0.1-100 GeV energy band. We confirm that flat spectrum radio quasars have steeper spectra than BL Lacertae objects with an average index of 2.48 ± 0.02 versus 2.18 ± 0.02. Using several methods, we build the deepest source count distribution at GeV energies, deriving that the intrinsic source (i.e., blazar) surface density at F 100 ≥ 10–9 ph cm–2 s–1 is 0.12+0.03 –0.02 deg–2. The integration of the source count distribution yields that point sources contribute 16(±1.8)% (±7% systematic uncertainty) of the GeV isotropic diffuse background. At the fluxes currently reached by LAT, we can rule out the hypothesis that pointlike sources (i.e., blazars) produce a larger fraction of the diffuse emission.

Authors:
 [1]
  1. Naval Research Lab. (NRL), Washington, DC (United States); et al.
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1357530
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 720; Journal Issue: 1; Journal ID: ISSN 0004-637X
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS

Citation Formats

Abdo, A. A. The Fermi -Lat High-Latitude Survey: Source Count Distributions And The Origin Of The Extragalactic Diffuse Background. United States: N. p., 2010. Web. doi:10.1088/0004-637X/720/1/435.
Abdo, A. A. The Fermi -Lat High-Latitude Survey: Source Count Distributions And The Origin Of The Extragalactic Diffuse Background. United States. doi:https://doi.org/10.1088/0004-637X/720/1/435
Abdo, A. A. Wed . "The Fermi -Lat High-Latitude Survey: Source Count Distributions And The Origin Of The Extragalactic Diffuse Background". United States. doi:https://doi.org/10.1088/0004-637X/720/1/435. https://www.osti.gov/servlets/purl/1357530.
@article{osti_1357530,
title = {The Fermi -Lat High-Latitude Survey: Source Count Distributions And The Origin Of The Extragalactic Diffuse Background},
author = {Abdo, A. A.},
abstractNote = {This is the first of a series of papers aimed at characterizing the populations detected in the high-latitude sky of the Fermi-LAT survey. In this work, we focus on the intrinsic spectral and flux properties of the source sample. We show that when selection effects are properly taken into account, Fermi sources are on average steeper than previously found (e.g., in the bright source list) with an average photon index of 2.40 ± 0.02 over the entire 0.1-100 GeV energy band. We confirm that flat spectrum radio quasars have steeper spectra than BL Lacertae objects with an average index of 2.48 ± 0.02 versus 2.18 ± 0.02. Using several methods, we build the deepest source count distribution at GeV energies, deriving that the intrinsic source (i.e., blazar) surface density at F 100 ≥ 10–9 ph cm–2 s–1 is 0.12+0.03 –0.02 deg–2. The integration of the source count distribution yields that point sources contribute 16(±1.8)% (±7% systematic uncertainty) of the GeV isotropic diffuse background. At the fluxes currently reached by LAT, we can rule out the hypothesis that pointlike sources (i.e., blazars) produce a larger fraction of the diffuse emission.},
doi = {10.1088/0004-637X/720/1/435},
journal = {Astrophysical Journal},
number = 1,
volume = 720,
place = {United States},
year = {2010},
month = {8}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Citation Metrics:
Cited by: 146 works
Citation information provided by
Web of Science

Save / Share:

Works referenced in this record:

BRIGHT ACTIVE GALACTIC NUCLEI SOURCE LIST FROM THE FIRST THREE MONTHS OF THE FERMI LARGE AREA TELESCOPE ALL-SKY SURVEY
journal, July 2009


FERMI LAT OBSERVATION OF DIFFUSE GAMMA RAYS PRODUCED THROUGH INTERACTIONS BETWEEN LOCAL INTERSTELLAR MATTER AND HIGH-ENERGY COSMIC RAYS
journal, September 2009


DETECTION OF GAMMA-RAY EMISSION FROM THE STARBURST GALAXIES M82 AND NGC 253 WITH THE LARGE AREA TELESCOPE ON FERMI
journal, January 2010


FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG
journal, May 2010

  • Abdo, A. A.; Ackermann, M.; Ajello, M.
  • The Astrophysical Journal Supplement Series, Vol. 188, Issue 2
  • DOI: 10.1088/0067-0049/188/2/405

SPECTRAL PROPERTIES OF BRIGHT FERMI -DETECTED BLAZARS IN THE GAMMA-RAY BAND
journal, January 2010


Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived from First-Year Fermi Large Area Telescope Data
journal, March 2010


THE FIRST CATALOG OF ACTIVE GALACTIC NUCLEI DETECTED BY THE FERMI LARGE AREA TELESCOPE
journal, April 2010


THE VELA PULSAR: RESULTS FROM THE FIRST YEAR OF FERMI LAT OBSERVATIONS
journal, March 2010


Impact of astrophysical processes on the gamma-ray background from dark matter annihilations
journal, July 2007


BAT X‐Ray Survey. I. Methodology and X‐Ray Identification
journal, May 2008

  • Ajello, M.; Greiner, J.; Kanbach, G.
  • The Astrophysical Journal, Vol. 678, Issue 1
  • DOI: 10.1086/529418

THE EVOLUTION OF SWIFT /BAT BLAZARS AND THE ORIGIN OF THE MeV BACKGROUND
journal, June 2009


THE LARGE AREA TELESCOPE ON THE FERMI GAMMA-RAY SPACE TELESCOPE MISSION
journal, May 2009


Energy spectra of X-ray clusters of galaxies
journal, November 1976


Non-baryonic dark matter: observational evidence and detection methods
journal, April 2000


Nonthermal Particles and Radiation Produced by Cluster Merger Shocks
journal, September 2003

  • Berrington, Robert C.; Dermer, Charles D.
  • The Astrophysical Journal, Vol. 594, Issue 2
  • DOI: 10.1086/376981

The XMM‐Newton Wide‐Field Survey in the COSMOS Field. II. X‐Ray Data and the log  N ‐log  S Relations
journal, September 2007

  • Cappelluti, N.; Hasinger, G.; Brusa, M.
  • The Astrophysical Journal Supplement Series, Vol. 172, Issue 1
  • DOI: 10.1086/516586

The Luminosity Function of the EGRET Gamma‐Ray Blazars
journal, April 1998

  • Chiang, J.; Mukherjee, R.
  • The Astrophysical Journal, Vol. 496, Issue 2
  • DOI: 10.1086/305403

1D, 2D, 3D wavelet methods for gamma-ray source analysis
conference, January 2007

  • Ciprini, S.; Tosti, G.; Marcucci, F.
  • THE FIRST GLAST SYMPOSIUM, AIP Conference Proceedings
  • DOI: 10.1063/1.2757444

A multidimensional unfolding method based on Bayes' theorem
journal, August 1995

  • D'Agostini, G.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 362, Issue 2-3
  • DOI: 10.1016/0168-9002(95)00274-X

Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for the Gamma-Ray Large Area Space Telescope
journal, April 2007

  • Dermer, Charles D.
  • The Astrophysical Journal, Vol. 659, Issue 2
  • DOI: 10.1086/512533

The Correction of Statistics for Accidental Error
journal, March 1940

  • Eddington, A. S.
  • Monthly Notices of the Royal Astronomical Society, Vol. 100, Issue 5
  • DOI: 10.1093/mnras/100.5.354

The pulsar contribution to the gamma-ray background
journal, January 2010

  • Faucher-Giguère, Claude-André; Loeb, Abraham
  • Journal of Cosmology and Astroparticle Physics, Vol. 2010, Issue 01
  • DOI: 10.1088/1475-7516/2010/01/005

High-energy gamma-ray results from the second small astronomy satellite
journal, May 1975

  • Fichtel, C. E.; Hartman, R. C.; Kniffen, D. A.
  • The Astrophysical Journal, Vol. 198
  • DOI: 10.1086/153590

The gamma ray background from large scale structure formation
journal, September 2003


The Third EGRET Catalog of High‐Energy Gamma‐Ray Sources
journal, July 1999

  • Hartman, R. C.; Bertsch, D. L.; Bloom, S. D.
  • The Astrophysical Journal Supplement Series, Vol. 123, Issue 1
  • DOI: 10.1086/313231

On the Normalization of the Cosmic Star Formation History
journal, November 2006

  • Hopkins, Andrew M.; Beacom, John F.
  • The Astrophysical Journal, Vol. 651, Issue 1
  • DOI: 10.1086/506610

THE BLAZAR SEQUENCE AND THE COSMIC GAMMA-RAY BACKGROUND RADIATION IN THE FERMI ERA
journal, August 2009


The Cosmic MeV Gamma-Ray Background and Hard X-Ray Spectra of Active Galactic Nuclei: Implications for the Origin of Hot AGN Coronae
journal, November 2007

  • Inoue, Yoshiyuki; Totani, Tomonori; Ueda, Yoshihiro
  • The Astrophysical Journal, Vol. 672, Issue 1
  • DOI: 10.1086/525848

Supersymmetric dark matter
journal, March 1996


Gamma Rays from Intergalactic Shocks
journal, March 2003

  • Keshet, Uri; Waxman, Eli; Loeb, Abraham
  • The Astrophysical Journal, Vol. 585, Issue 1
  • DOI: 10.1086/345946

Cosmic γ-ray background from structure formation in the intergalactic medium
journal, May 2000


Optical spectroscopy and polarization of a new sample of optically bright flat radio spectrum sources
journal, July 1996

  • Marcha, M. J. M.; Browne, I. W. A.; Impey, C. D.
  • Monthly Notices of the Royal Astronomical Society, Vol. 281, Issue 2
  • DOI: 10.1093/mnras/281.2.425

Intergalactic shock acceleration and the cosmic gamma-ray background
journal, November 2002


The contribution of unresolved radio-loud AGN to the extragalactic diffuse gamma-ray background
journal, February 2000


Gamma‐Ray Luminosity Function of Blazars and the Cosmic Gamma‐Ray Background: Evidence for the Luminosity‐Dependent Density Evolution
journal, May 2006

  • Narumoto, Takuro; Totani, Tomonori
  • The Astrophysical Journal, Vol. 643, Issue 1
  • DOI: 10.1086/502708

The Guaranteed Gamma-Ray Background
journal, August 2002

  • Pavlidou, Vasiliki; Fields, Brian D.
  • The Astrophysical Journal, Vol. 575, Issue 1
  • DOI: 10.1086/342670

Simulating cosmic rays in clusters of galaxies – II. A unified scheme for radio haloes and relics with predictions of the γ-ray emission
journal, April 2008

  • Pfrommer, Christoph; Enßlin, Torsten A.; Springel, Volker
  • Monthly Notices of the Royal Astronomical Society, Vol. 385, Issue 3
  • DOI: 10.1111/j.1365-2966.2008.12956.x

EGRET Observations of the Extragalactic Gamma‐Ray Emission
journal, February 1998

  • Sreekumar, P.; Bertsch, D. L.; Dingus, B. L.
  • The Astrophysical Journal, Vol. 494, Issue 2
  • DOI: 10.1086/305222

The Gamma-Ray Background from Blazars: A New Look
journal, June 1996

  • Stecker, F. W.; Salamon, M. H.
  • The Astrophysical Journal, Vol. 464
  • DOI: 10.1086/177348

The Einstein Observatory Extended Medium-Sensitivity Survey. II - The optical identifications
journal, May 1991

  • Stocke, John T.; Morris, Simon L.; Gioia, I. M.
  • The Astrophysical Journal Supplement Series, Vol. 76
  • DOI: 10.1086/191582

A New Determination of the Extragalactic Diffuse Gamma‐Ray Background from EGRET Data
journal, October 2004

  • Strong, Andrew W.; Moskalenko, Igor V.; Reimer, Olaf
  • The Astrophysical Journal, Vol. 613, Issue 2
  • DOI: 10.1086/423196

The Starburst Contribution to the Extragalactic γ‐Ray Background
journal, January 2007

  • Thompson, Todd A.; Quataert, Eliot; Waxman, Eli
  • The Astrophysical Journal, Vol. 654, Issue 1
  • DOI: 10.1086/509068

Cosmological dark matter annihilations into γ rays: A closer look
journal, December 2002


Unified Schemes for Radio-Loud Active Galactic Nuclei
journal, June 1995

  • Urry, C. Megan; Padovani, Paolo
  • Publications of the Astronomical Society of the Pacific, Vol. 107
  • DOI: 10.1086/133630

The Large-Sample Distribution of the Likelihood Ratio for Testing Composite Hypotheses
journal, March 1938


    Works referencing / citing this record:

    Active galactic nuclei: what’s in a name?
    journal, August 2017

    • Padovani, P.; Alexander, D. M.; Assef, R. J.
    • The Astronomy and Astrophysics Review, Vol. 25, Issue 1
    • DOI: 10.1007/s00159-017-0102-9

    The gamma-ray spectral index changes for blazars
    journal, September 2012

    • Yang, JiangHe; Fan, JunHui; Nie, JianJun
    • Science China Physics, Mechanics and Astronomy, Vol. 55, Issue 11
    • DOI: 10.1007/s11433-012-4901-8

    Current and future constraints on dark matter from prompt and inverse-Compton photon emission in the isotropic diffuse gamma-ray background
    journal, February 2012


    Constraining extended gamma-ray emission from galaxy clusters: Extended gamma-ray emission in clusters
    journal, November 2012


    PROBING THE COSMIC X-RAY AND MeV GAMMA-RAY BACKGROUND RADIATION THROUGH THE ANISOTROPY
    journal, September 2013

    • Inoue, Yoshiyuki; Murase, Kohta; Madejski, Grzegorz M.
    • The Astrophysical Journal, Vol. 776, Issue 1
    • DOI: 10.1088/0004-637x/776/1/33

    Active galactic nuclei: what’s in a name?
    journal, August 2017

    • Padovani, P.; Alexander, D. M.; Assef, R. J.
    • The Astronomy and Astrophysics Review, Vol. 25, Issue 1
    • DOI: 10.1007/s00159-017-0102-9

    The gamma-ray spectral index changes for blazars
    journal, September 2012

    • Yang, JiangHe; Fan, JunHui; Nie, JianJun
    • Science China Physics, Mechanics and Astronomy, Vol. 55, Issue 11
    • DOI: 10.1007/s11433-012-4901-8

    PROBING THE COSMIC X-RAY AND MeV GAMMA-RAY BACKGROUND RADIATION THROUGH THE ANISOTROPY
    journal, September 2013

    • Inoue, Yoshiyuki; Murase, Kohta; Madejski, Grzegorz M.
    • The Astrophysical Journal, Vol. 776, Issue 1
    • DOI: 10.1088/0004-637x/776/1/33

    Current and future constraints on dark matter from prompt and inverse-Compton photon emission in the isotropic diffuse gamma-ray background
    journal, February 2012


    The radio-γ-ray connection in Fermi blazars: γ-ray-radio flux correlation in blazars
    journal, March 2011


    Constraining extended gamma-ray emission from galaxy clusters: Extended gamma-ray emission in clusters
    journal, November 2012


    Unveiling the Nature of the Unidentified Gamma-Ray Sources. v. Analysis of the Radio Candidates with the Kernel Density Estimation
    journal, October 2013

    • Massaro, F.; D'Abrusco, R.; Paggi, A.
    • The Astrophysical Journal Supplement Series, Vol. 209, Issue 1
    • DOI: 10.1088/0067-0049/209/1/10

    TOMOGRAPHY OF THE FERMI -LAT γ -RAY DIFFUSE EXTRAGALACTIC SIGNAL VIA CROSS CORRELATIONS WITH GALAXY CATALOGS
    journal, March 2015

    • Xia, Jun-Qing; Cuoco, Alessandro; Branchini, Enzo
    • The Astrophysical Journal Supplement Series, Vol. 217, Issue 1
    • DOI: 10.1088/0067-0049/217/1/15

    Constraining very heavy dark matter using diffuse backgrounds of neutrinos and cascaded gamma rays
    journal, October 2012


    Unidentified sources in the Fermi-LAT second source catalog: the case for DM subhalos
    journal, November 2012


    Star-forming galaxies as the origin of diffuse high-energy backgrounds: gamma-ray and neutrino connections, and implications for starburst history
    journal, September 2014

    • Tamborra, Irene; Ando, Shin'ichiro; Murase, Kohta
    • Journal of Cosmology and Astroparticle Physics, Vol. 2014, Issue 09
    • DOI: 10.1088/1475-7516/2014/09/043

    Power spectrum tomography of dark matter annihilation with local galaxy distribution
    journal, October 2014


    Background model systematics for the Fermi GeV excess
    journal, March 2015

    • Calore, Francesca; Cholis, Ilias; Weniger, Christoph
    • Journal of Cosmology and Astroparticle Physics, Vol. 2015, Issue 03
    • DOI: 10.1088/1475-7516/2015/03/038

    Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse γ-ray emission
    journal, June 2015


    Limits on dark matter annihilation signals from the Fermi LAT 4-year measurement of the isotropic gamma-ray background
    journal, September 2015


    On The gamma-ray emission from Reticulum II and other dwarf galaxies
    journal, September 2015


    A case for radio galaxies as the sources of IceCube's astrophysical neutrino flux
    journal, September 2016


    Constraints on decaying dark matter from the isotropic gamma-ray background
    journal, March 2019


    Gamma-Ray Polarimetry: A New Window for the Nonthermal Universe
    journal, September 2019

    • Ilie, Cosmin
    • Publications of the Astronomical Society of the Pacific, Vol. 131, Issue 1005
    • DOI: 10.1088/1538-3873/ab2a3a

    Extragalactic gamma-ray background from star-forming galaxies: Will empirical scalings suffice?
    journal, December 2018

    • Komis, I.; Pavlidou, V.; Zezas, A.
    • Monthly Notices of the Royal Astronomical Society, Vol. 483, Issue 3
    • DOI: 10.1093/mnras/sty3354

    The luminosity function and formation rate of a complete sample of long gamma-ray bursts
    journal, July 2019

    • Lan, Guang-Xuan; Zeng, Hou-Dun; Wei, Jun-Jie
    • Monthly Notices of the Royal Astronomical Society, Vol. 488, Issue 4
    • DOI: 10.1093/mnras/stz2011

    Gamma-ray luminosity function of BL Lac objects and contribution to the extragalactic gamma-ray background
    journal, September 2019

    • Qu, Yankun; Zeng, Houdun; Yan, Dahai
    • Monthly Notices of the Royal Astronomical Society, Vol. 490, Issue 1
    • DOI: 10.1093/mnras/stz2651

    Realistic estimation for the detectability of dark matter subhalos using Fermi-LAT catalogs
    journal, September 2017


    Star-forming galaxies significantly contribute to the isotropic gamma-ray background
    journal, October 2017


    The Lyman α forest in a blazar-heated Universe: Lyman α forest in a blazar-heated Universe
    journal, May 2012

    • Puchwein, Ewald; Pfrommer, Christoph; Springel, Volker
    • Monthly Notices of the Royal Astronomical Society, Vol. 423, Issue 1
    • DOI: 10.1111/j.1365-2966.2012.20738.x

    Deriving the Contribution of Blazars to the Fermi -LAT Extragalactic γ -ray Background at E > 10 GeV with Efficiency Corrections and Photon Statistics
    journal, March 2018


    The Extragalactic Gamma-Ray Background from Core-dominated Radio Galaxies
    journal, July 2019

    • Stecker, Floyd W.; Shrader, Chris R.; Malkan, Matthew. A.
    • The Astrophysical Journal, Vol. 879, Issue 2
    • DOI: 10.3847/1538-4357/ab23ee

    Complementarity of Stacking and Multiplet Constraints on the Blazar Contribution to the Cumulative High-energy Neutrino Intensity
    journal, February 2020

    • Yuan, Chengchao; Murase, Kohta; Mészáros, Peter
    • The Astrophysical Journal, Vol. 890, Issue 1
    • DOI: 10.3847/1538-4357/ab65ea