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Title: The TeV blazar measurement of the extragalactic background light

Gamma-rays propagating through space are likely to be extinguished via electron-positron pair production off of the ambient extragalactic background light (EBL). The spectrum of the EBL is produced by starlight (and starlight reprocessed by dust) from all galaxies throughout the history of the Universe. The attenuation of 40–400 GeV gamma-rays has been observed by Fermi and used to measure the EBL spectrum over energies 1 eV–10 eV out to redshift z ∼ 1. Measurements of several TeV blazers are consistent with attenuation, attributed to the EBL at redshift z ∼ 0.1. Here we simultaneously analyze a set of TeV blazers at z ∼ 0.1 to measure the optical depth for 100 GeV–10 TeV gamma-rays, which interact with EBL of energies 0.05 eV–5 eV. Using a suite of models for the EBL, we show that the optical depth indicated by TeV blazar attenuation is in good agreement with the optical depths measured by Fermi at lower gamma-ray energies and higher redshifts.
Authors:
;  [1]
  1. Department of Physics, The Ohio State University, Columbus, OH, 43210 (United States)
Publication Date:
OSTI Identifier:
22369867
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2013; Journal Issue: 12; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ATTENUATION; GALAXIES; GAMMA RADIATION; GEV RANGE; PAIR PRODUCTION; RED SHIFT; SPACE; TEV RANGE; UNIVERSE; VISIBLE RADIATION