Armstrong, Thomas and Brown, Anthony M. and Chadwick, Paula M. (2017) 'Fermi-LAT high-z active galactic nuclei and the extragalactic background light.', Monthly notices of the Royal Astronomical Society., 470 (4). pp. 4089-4098.
Observations of distant gamma-ray sources are hindered by the presence of the extragalactic background light (EBL). In order to understand the physical processes that result in the observed spectrum of sources, it is imperative that a good understanding of the EBL is included. In this work, an investigation into the imprint of the EBL on the observed spectra of high-redshift Fermi-LAT active galactic nuclei is presented. By fitting the spectrum below ∼10 GeV, an estimation of the unabsorbed intrinsic source spectrum is obtained; by applying this spectrum to data up to 300 GeV, it is then possible to derive a scaling factor for different EBL models. A second approach uses five sources (PKS 0426−380, 4C +55.17, Ton 116, PG 1246+586 and RBS 1432) that were found to exhibit very high energy (VHE) emission (Eγ > 100 GeV). Through Monte Carlo simulations, it is shown that the observation of VHE photons, despite the large distances of these objects, is consistent with current EBL models. Many of these sources would be observable with the upcoming ground-based observatory, the Cherenkov Telescope Array, leading to a better understanding of the EBL.
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|Publisher Web site:||https://doi.org/10.1093/mnras/stx1309|
|Publisher statement:||This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.|
|Date accepted:||24 May 2017|
|Date deposited:||11 October 2017|
|Date of first online publication:||29 May 2017|
|Date first made open access:||11 October 2017|
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