Intergalactic absorption and blazar gamma-ray spectra
Abstract
The distribution of TeV spectral slopes versus redshift for currently known TeV blazars (16 sources with z<0.21, and one with z>0.25) is essentially a scatter plot with hardly any hint of a global trend. We suggest that this is the outcome of two combined effects of intergalactic gamma-gamma absorption, plus an inherent feature of the SSC (synchro-self-Compton) process of blazar emission. First, flux dimming introduces a bias that favors detection of progressively more flaring sources at higher redshifts. According to mainstream SSC models, more flaring source states imply sources with flatter TeV slopes. This results in a structured relation between intrinsic TeV slope and redshift. The second effect, spectral steepening by intergalactic absorption, affects sources progressively with distance and effectively wipes out the intrinsic slope-redshift correlation.
Cite
@article{arxiv.0711.2317,
title = {Intergalactic absorption and blazar gamma-ray spectra},
author = {Massimo Persic and Alessandro De Angelis},
journal= {arXiv preprint arXiv:0711.2317},
year = {2009}
}
Comments
A&A, in press (accepted Jan 29, 2008): 6 pages, 2 figures. One source, published subsequent to acceptance, added