Astronomy and Astrophysics – Astrophysics
Scientific paper
2007-05-25
Astronomy and Astrophysics
Astrophysics
8 pages, 7 figures, accepted by A&A, final version
Scientific paper
10.1051/0004-6361:20065605
Very high energy gamma-rays from blazars traversing cosmological distances through the metagalactic radiation field can convert into electron-positron pairs in photon-photon collisions. The converted gamma-rays initiate electromagnetic cascades driven by inverse-Compton scattering off the microwave background photons. Using a model for the time-dependent metagalactic radiation field consistent with all currently available far-infrared-to-optical data, we calculate the cascade contribution from faint, unresolved high- and low-peaked blazars to the extragalactic gamma-ray background as measured by EGRET. For low-peaked blazars, we adopt a spectral index consistent with the mean spectral index of EGRET detected blazars, and the luminosity function determined by Chiang and Mukherjee (1998). For high-peaked blazars, we adopt template spectra matching prototype sources observed with air-Cherenkov telescopes up to 30 TeV, and a luminosity function based on X-ray measurements. The low number of about 20 for nearby high-peaked blazars with a flux exceeding 10^-11 cm^-2 s^-1 above 300 GeV inferred from the luminosity function is consistent with the results from air-Cherenkov telescope observations. Including the cascade emission from higher redshifts, the total high-peaked blazar contribution to the observed gamma-ray background at GeV energies can account up to about 30.
Kneiske Tanja M.
Mannheim Karl
No associations
LandOfFree
BL Lac Contribution to the Extragalactic Gamma-Ray Background does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with BL Lac Contribution to the Extragalactic Gamma-Ray Background, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and BL Lac Contribution to the Extragalactic Gamma-Ray Background will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-680187