| Issue |
A&A
Volume 413, Number 3, January III 2004
|
|
|---|---|---|
| Page(s) | 807 - 815 | |
| Section | Cosmology (including clusters of galaxies) | |
| DOI | https://doi.org/10.1051/0004-6361:20031542 | |
| Published online | 07 January 2004 | |
Implications of cosmological gamma-ray absorption
II. Modification of gamma-ray spectra
1
Universität Würzburg, Am Hubland, 97057 Würzburg, Germany
2
Clemson University, Clemson, SC 29634-0978, USA
Corresponding author: T. M. Kneiske, kneiske@astro.uni-wuerzburg.de
Received:
10
April
2003
Accepted:
16
September
2003
Bearing on the model for the time-dependent metagalactic radiation field developed in the first paper of this series, we compute the gamma-ray attenuation due to pair production in photon-photon scattering. Emphasis is on the effects of varying the star formation rate and the fraction of UV radiation assumed to escape from the star forming regions, the latter being important mainly for high-redshift sources. Conversely, we investigate how the metagalactic radiation field can be measured from the gamma-ray pair creation cutoff as a function of redshift, the Fazio-Stecker relation. For three observed TeV-blazars (Mkn 501, Mkn 421, H1426+428) we study the effects of gamma-ray attenuation on their spectra in detail.
Key words: cosmology: diffuse radiation / galaxies: BL Lacertae objects: general / galaxies: BL Lacertae objects: individual: Mkn 421, Mkn 501, H1426+428
© ESO, 2004
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