Models of the Contribution of Blazars to the Anisotropy of the Extragalactic Diffuse Gamma-ray Background

Abstract

We study the relation between the measured anisotropies in the extragalactic diffuse gamma-ray background (DGRB) and the DGRB spectral intensity, and their potential origin from the unresolved blazar population. Using a physical-evolution model for blazars with a luminosity dependent evolution (LDDE) and an observationally-determined luminosity-dependent blazar spectral energy distribution (SED), we find that blazars can account for the observed anisotropy of the DGRB consistent with their observed source-count distribution, but are in turn constrained in contributing significantly to the observed DGRB intensity. For the best-fit LDDE model accounting for the DGRB anisotropy and source-count distribution, blazars only contribute 5.7^{+2.1}_{-1.0}% (68% CL) of the DGRB intensity above 1 GeV. Requiring a higher fraction of the DGRB intensity contribution by blazars overproduces the DGRB anisotropy, and therefore blazars in the LDDE+SED-sequence model cannot simultaneously account for the DGRB intensity as well as anisotropy. We discuss the limitations of LDDE models. However, these models do not require the many unjustified and observationally-inconsistent simplifying assumptions---including a single power law for all blazar spectra and a simple broken power-law model for their source-count distribution---that are present in much previous work.

17 pages, 5 figures; v2: updated KS-test comparison with the blazar redshift distribution and flux index distribution; removal of gamma1 < 0 parameter space, with small shift in best fit parameters; added references and discussion; matches published version in JCAP

References in corpus (12)

• The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data
• GeV Observations of Star-forming Galaxies with \textit{Fermi} LAT
• The Fermi-LAT high-latitude Survey: Source Count Distributions and the Origin of the Extragalactic Diffuse Background
• Pre-launch estimates for GLAST sensitivity to Dark Matter annihilation signals
• Dark matter annihilation or unresolved astrophysical sources? Anisotropy probe of the origin of cosmic gamma-ray background
• Cosmic Gamma-Ray Background from Star-Forming Galaxies
• Joint anisotropy and source count constraints on the contribution of blazars to the diffuse gamma-ray background
• Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for GLAST
• Gamma-Ray and Neutrino Backgrounds as Probes of the High-Energy Universe: Hints of Cascades, General Constraints, and Implications for TeV Searches
• Anisotropy probe of galactic and extra-galactic Dark Matter annihilations
• Angular Anisotropies in the Cosmic Gamma-ray Background as a Probe of its Origin
• Upper Limit on the Cosmological Gamma-ray Background

Cited by in corpus (40)

• Diffuse Neutrino Intensity from the Inner Jets of Active Galactic Nuclei: Impacts of External Photon Fields and the Blazar Sequence
• A review of indirect searches for particle dark matter
• The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation
• Limits on Dark Matter Annihilation Signals from the Fermi LAT 4-year Measurement of the Isotropic Gamma-Ray Background
• The nature of the Diffuse Gamma-Ray Background
• Sensitivity Projections for Dark Matter Searches with the Fermi Large Area Telescope
• Constraints on Decaying Dark Matter from the Isotropic Gamma-Ray Background
• On The Gamma-Ray Emission From Reticulum II and Other Dwarf Galaxies
• Robust Constraints and Novel Gamma-Ray Signatures of Dark Matter That Interacts Strongly With Nucleons
• A novel approach in the WIMP quest: Cross-Correlation of Gamma-Ray Anisotropies and Cosmic Shear
• Cross-Correlation of Cosmic Shear and Extragalactic Gamma-ray Background: Constraints on the Dark Matter Annihilation Cross-Section
• The angular power spectrum of the diffuse gamma-ray emission as measured by the Fermi Large Area Telescope and constraints on its Dark Matter interpretation
• A Case for Radio Galaxies as the Sources of IceCube's Astrophysical Neutrino Flux
• Unveiling the Gamma-ray Source Count Distribution Below the Fermi Detection Limit with Photon Statistics
• Constraining dark matter annihilation with the isotropic $\gamma$-ray background: updated limits and future potential
• Tomographic-spectral approach for dark matter detection in the cross-correlation between cosmic shear and diffuse gamma-ray emission
• Active Galactic Nuclei and the Origin of IceCube's Diffuse Neutrino Flux
• Dissecting the Gamma-Ray Background in Search of Dark Matter
• Radio Galaxies Dominate the High-Energy Diffuse Gamma-Ray Background
• Fermi-LAT gamma-ray anisotropy and intensity explained by unresolved Radio-Loud Active Galactic Nuclei
• Tomographic imaging of the Fermi-LAT gamma-ray sky through cross-correlations: A wider and deeper look
• Probing the Cosmic X-ray and MeV Gamma-ray Background Radiation through the Anisotropy
• Characterizing the local gamma-ray Universe via angular cross-correlations
• Angular Power Spectra with Finite Counts
• Improving the Sensitivity of Gamma-Ray Telescopes to Dark Matter Annihilation in Dwarf Spheroidal Galaxies
• Lower Limits on the Anisotropy of the Extragalactic Gamma-Ray Background implied by the 2FGL and 1FHL Catalogs
• Astrophysical interpretation of the anisotropies in the unresolved gamma-ray background
• The correlation of extragalactic $\gamma$-rays with cosmic matter density distributions from weak-gravitational lensing
• A Determination of the Gamma-ray Flux and Photon Spectral Index Distributions of Blazars from the Fermi-LAT 3LAC
• Gamma-ray anisotropies from dark matter in the Milky Way: the role of the radial distribution
• Prospects for future very high-energy gamma-ray sky survey: impact of secondary gamma rays
• Novel Techniques for Decomposing Diffuse Backgrounds
• High-Energy Gamma Rays and Neutrinos from Nearby Radio Galaxies
• Harnessing the Population Statistics of Subhalos to Search for Annihilating Dark Matter
• Constraints on cosmic ray loading and PeV neutrino production in blazars
• High-Energy Neutrino Emission from Espresso-Reaccelerated Ions in Jets of Active Galactic Nuclei
• Analysis of Fermi-LAT data from Tucana-II: Possible constraints on the Dark Matter models with an intriguing hint of a signal
• Gamma-Rays from Star Forming Activity Appear to Outshine Misaligned Active Galactic Nuclei
• Approximate Bayesian Computation Applied to the Diffuse Gamma-ray Sky
• The Contribution From TeV Halos to the Isotropic Gamma-Ray Background