The contribution from blazar cascade emission to the extragalactic gamma-ray background: What a role does the extragalactic magnetic field play?

Abstract

We estimate the contribution to the extragalactic gamma-ray background (EGRB) from both intrinsic and cascade emissions produced by blazars using a simple semi- analysis method for two models of the blazar gamma-ray luminosity function (GLF). For the cascade emission, we consider two possible contributions: one is due to that the flux of the cascade emission is lower than the Fermi LAT sensitivity (case I), which is independent on the extragalactic magnetic field (EGMF), another is due to the fact that the flux of the cascade emission is larger than the Fermi LAT sensitivity but the emission angle is larger than LAT point-spread-function (PSF) angle (case II), which depends on the EGMF. Our results indicate that (1) blazar contribution to the EGRB is dominant although it depends on the GLF model and the EGMF; (2) the EGMF plays an important role in estimating the contribution from the cascade emission produced by blazars, the contribution from the cascade emission will significantly alter the EGRB spectrum when the strength of the EGMF is large enough (say BEGMF > 10-12 G); and (3) since the cascade emission in case II reaches a saturation when the strength of the EGMF is ? 10-11 G, it is very possible that the contribution from the cascade emission produced by blazars can be considered as another method to probe the upper limit of the strength of the EGMF.

6 pages, 3 figures. Accepted for publication in MNRAS

References in corpus (21)

• Evidence for strong extragalactic magnetic fields from Fermi observations of TeV blazars
• Extragalactic Background Light Inferred from AEGIS Galaxy SED-type Fractions
• The Spectrum of the Isotropic Diffuse Gamma-Ray Emission Derived From First-Year Fermi Large Area Telescope Data
• EGMF Constraints from Simultaneous GeV-TeV Observations of Blazars
• Lower limit on the strength and filling factor of extragalactic magnetic fields
• Time Delay of Cascade Radiation for TeV Blazars and the Measurement of the Intergalactic Magnetic Field
• The Fermi-LAT high-latitude Survey: Source Count Distributions and the Origin of the Extragalactic Diffuse Background
• Contribution of the Gamma-ray Loud Radio Galaxies Core Emissions to the Cosmic MeV and GeV Gamma-Ray Background Radiation
• The Starburst Contribution to the Extra-Galactic Gamma-Ray Background
• The radio/gamma-ray connection in Active Galactic Nuclei in the era of the Fermi Large Area Telescope
• Cosmic Gamma-Ray Background from Star-Forming Galaxies
• Components of the Extragalactic Gamma Ray Background
• Statistics of Cosmological Black Hole Jet Sources: Blazar Predictions for GLAST
• ELMAG: A Monte Carlo simulation of electromagnetic cascades on the extragalactic background light and in magnetic fields
• The radio/gamma-ray connection in Fermi-blazars
• Contribution from Star-Forming Galaxies to the Cosmic Gamma-Ray Background Radiation
• Two-Step Acceleration Model of Cosmic Rays at Middle-Aged SNR
• A New Model for Gamma-Ray Cascades in Extragalactic Magnetic Fields
• BL Lac Contribution to the Extragalactic Gamma-Ray Background
• The Effect of Blazar Spectral Breaks on the Blazar Contribution to the Extragalactic Gamma-ray Background
• How many radio-loud quasars can be detected by the Gamma-Ray Large Area Space Telescope?

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• Gamma-Ray and Neutrino Backgrounds as Probes of the High-Energy Universe: Hints of Cascades, General Constraints, and Implications for TeV Searches
• Constraints on Dark Matter Annihilation/Decay from the Isotropic Gamma-Ray Background
• Gamma-ray luminosity function of BL Lac objects and contribution to the extragalactic gamma-ray background
• Impact of Plasma Instability on Constraint of the Intergalactic Magnetic Field
• Diffuse Pionic Gamma-Ray Emission from Large Scale Structures in the FERMI Era