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Title: Intergalactic magnetic fields and gamma-ray observations of extreme TeV blazars

The intergalactic magnetic field (IGMF) in cosmic voids can be indirectly probed through its effect on electromagnetic cascades initiated by a source of teraelectronvolt (TeV) gamma-rays, such as active galactic nuclei (AGNs). AGNs that are sufficiently luminous at TeV energies, 'extreme TeV blazars', can produce detectable levels of secondary radiation from inverse Compton scattering of the electrons in the cascade, provided that the IGMF is not too large. We review recent work in the literature that utilizes this idea to derive constraints on the IGMF for three TeV-detected blazars, 1ES 0229+200, 1ES 1218+304, and RGB J0710+591, and we also investigate four other hard-spectrum TeV blazars in the same framework. Through a recently developed, detailed, three-dimensional particle-tracking Monte Carlo code, incorporating all major effects of QED and cosmological expansion, we research the effects of major uncertainties, such as the spectral properties of the source, uncertainty in the ultraviolet and far-infrared extragalactic background light, undersampled very high energy (energy ≥100 GeV) coverage, past history of gamma-ray emission, source versus observer geometry, and the jet AGN Doppler factor. The implications of these effects on the recently reported lower limits of the IGMF are thoroughly examined to conclude that the presently available data aremore » compatible with a zero-IGMF hypothesis.« less
Authors:
;  [1] ; ;  [2] ;  [3]
  1. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
  2. Enrico Fermi Institute, University of Chicago, Chicago, IL 60637 (United States)
  3. Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, CA 94720 (United States)
Publication Date:
OSTI Identifier:
22369991
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 796; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BACKGROUND RADIATION; COMPTON EFFECT; EMISSION; EXPANSION; GALAXY NUCLEI; GAMMA RADIATION; GEV RANGE; HYPOTHESIS; INTERGALACTIC SPACE; MAGNETIC FIELDS; MONTE CARLO METHOD; QUANTUM ELECTRODYNAMICS; SPECTRA; STARS; TEV RANGE; ULTRAVIOLET RADIATION; UNIVERSE; VISIBLE RADIATION