Volume 483, Number 1, May III 2008
|Page(s)||1 - 5|
|Published online||04 February 2008|
Intergalactic absorption and blazar γ-ray spectra
INAF and INFN, via G.B.Tiepolo 11, 34143 Trieste, Italy e-mail: email@example.com
2 Università di Udine and INFN, via delle Scienze 208, 33100 Udine, Italy
3 Instituto Superior Técnico, Lisboa, Portugal
Accepted: 29 January 2008
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 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.
Key words: galaxies: BL Lacertae objects: general / gamma rays: observations / cosmology: diffuse radiation
© ESO, 2008
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.