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Title: Sensitivity of the Cherenkov Telescope Array to the detection of axion-like particles at high gamma-ray opacities

Extensions of the Standard Model of particles commonly predict the existence of axion(-like) particles (ALPs) that could be detected through their coupling to photons in external magnetic fields. This coupling could lead to modifications of γ-ray spectra from extragalactic sources. Above a certain energy, the γ-ray flux should be exponentially damped due to the interaction with photons of background radiations fields. ALPs, on the other hand, propagate unimpeded over cosmological distances and a reconversion into γ-rays could lead to an additional component in the spectra. Here, we present the sensitivity of the proposed Cherenkov Telescope Array (CTA) to detect this spectral hardening. Using the full instrumental response functions of CTA, a combined likelihood analysis of four γ-ray sources shows that a significant detection of the ALP signal is possible for couplings g{sub aγ} ≳ 2 × 10{sup −11} GeV{sup −1} and ALP masses m{sub a} ∼< 100 neV. We discuss the dependency of these values on different model assumptions and magnetic-field scenarios and identify the best observation strategy to search for an ALP induced boost of the γ-ray flux.
Authors:
;  [1]
  1. The Oskar Klein Center for Cosmoparticle Physics, Department of Physics, Roslagstullsbacken 21, Stockholm University, Albanova, SE-10691 Stockholm (Sweden)
Publication Date:
OSTI Identifier:
22382090
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; 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; BACKGROUND RADIATION; DETECTION; DISTANCE; GAMMA RADIATION; INTERACTIONS; MAGNETIC FIELDS; MASS; MODIFICATIONS; OPACITY; PHOTONS; RESPONSE FUNCTIONS; SENSITIVITY; SIGNALS; SPECTRAL HARDENING; STANDARD MODEL; TELESCOPES