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Title: Extragalactic photon-ALP conversion at CTA energies

Magnetic fields in extragalactic space between galaxy clusters may induce conversions between photons and axion-like particles (ALPs), thereby shielding the photons from absorption on the extragalactic background light. For TeV gamma rays, the oscillation length (l osc) of the photon-ALP system becomes inevitably of the same order as the coherence length of the magnetic field l and the length over which the field changes significantly (transition length l t) due to refraction on background photons. We derive exact statistical evolution equations for the mean and variance of the photon and ALP transfer functions in the non-adiabatic regime (l osc ~ l >> l t). We also make analytical predictions for the transfer functions in the quasi-adiabatic regime (l osc <t). Our results are important in light of the upcoming Cherenkov Telescope Array (CTA), and may also be applied to models with non-zero ALP masses.
 [1] ;  [1] ;  [2]
  1. Max-Planck-Inst. fur Physik, Munich (Germany)
  2. Max-Planck-Inst. fur Physik, Munich (Germany); SLAC National Accelerator Lab., Menlo Park, CA (United States)
Publication Date:
Report Number(s):
Journal ID: ISSN 1475-7516
Grant/Contract Number:
AC02-76SF00515; EXC 153; H2020-MSCAITN- 2015/674896-ELUSIVES
Accepted Manuscript
Journal Name:
Journal of Cosmology and Astroparticle Physics
Additional Journal Information:
Journal Volume: 2017; Journal Issue: 01; Journal ID: ISSN 1475-7516
Institute of Physics (IOP)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE; German Research Foundation (DFG); European Union (EU)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; transparency of the Universe to high-energy photons; axion-like particles; photon-ALP conversion; photon-photon refraction; extragalactic magnetic fields
OSTI Identifier: