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arXiv · 0711.2317

Intergalactic absorption and blazar gamma-ray spectra

Massimo Persic·Alessandro De Angelis
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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.

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Massimo Persic, Alessandro De Angelis. 2008-03-24. Intergalactic absorption and blazar gamma-ray spectra. https://doi.org/10.1051/0004-6361:20079074

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