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Derivation of a Relation for the Steepening of TeV Selected Blazar Gamma-Ray Spectra with Energy and RedshiftWe derive a relation for the steepening of blazar gamma-ray spectra between the multi-GeV Fermi energy range and the TeV energy range observed by atmospheric Cerenkov telescopes. The change in spectral index is produced by two effects: (1) an intrinsic steepening, independent of redshift, owing to the properties of emission and absorption in the source, and (2) a redshift-dependent steepening produced by intergalactic pair production interactions of blazar gamma-rays with low energy photons of the "intergalactic background light" (IBL). Given this relation, with good enough data on the mean gamma-ray SED of TeV Selected BL Lacs, the redshift evolution of the IBL can, in principle, be determined independently of stellar evolution models. We apply our relation to the results of new Fermi observations of TeV selected blazars.
Document ID
20100014243
Acquisition Source
Goddard Space Flight Center
Document Type
Conference Paper
Authors
Stecker, F.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2010
Subject Category
Astronomy
Meeting Information
Meeting: HEAD 2010
Location: Kona, HI
Country: United States
Start Date: March 1, 2010
End Date: March 4, 2010
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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