文章基本信息

标题：Extragalactic background light models and GeV-TeV observation of blazars
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作者：K. K. Singh ; P. J. Meintjes
期刊名称：NRIAG Journal of Astronomy and Geophysics
印刷版ISSN：2090-9977
电子版ISSN：2090-9985
出版年度：2020
卷号：9
期号：1
页码：309-320
DOI：10.1080/20909977.2020.1743468
语种：English
出版社：Elsevier
摘要：In this work, we use two different methods to determine the opacity of the TeV gamma-rays caused by the extragalactic background light (EBL) via e—e+ production due to photon-photon interaction. The first method, Model-Dependent Approach, uses various EBL models for estimating the opacity as a function of the redshift and energy of the TeV photons. The second method, Model-Independent Approach, relies on using the simultaneous observations of blazars in the MeV-GeV energy range from the Fermi-LAT and in the TeV band from the ground-based gammaray telescopes. We make the underline assumption that the extrapolation of the LAT spectrum of blazars to TeV energies is either a good estimate or an upper limit for the intrinsic TeV spectrum of a source. We apply this method on the simultaneous observations of a few blazars at different redshifts to demonstrate a comparative study of six prominent EBL models. Opacities of the TeV photons predicted by the model-independent approach are systematically larger than the ones estimated from the modeldependent method. Therefore, the gamma-ray observations of blazars can be used to set a strict upper limit on the opacity of the Universe to the TeV photons at a given redshift.
关键词：Galaxies: blazars;observations: gamma-rays;general: EBL