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Title: Nuclear enhancement of the photon yield in cosmic ray interactions

The concept of the nuclear enhancement factor has been used since the beginning of γ-ray astronomy. It provides a simple and convenient way to account for the contribution of nuclei (A > 1) in cosmic rays (CRs) and in the interstellar medium (ISM) to the diffuse γ-ray emission. An accurate treatment of the dominant emission process, such as hadronic interactions of CRs with the ISM, enables one to study CR acceleration processes and CR propagation in the ISM, and provides a reliable background model for searches of new phenomena. The Fermi Large Area Telescope launched in 2008 provides excellent quality data in a wide energy range 30 MeV-1 TeV where the diffuse emission accounts for the majority of photons. Exploiting its data to the fullest requires a new study of the processes of γ-ray production in hadronic interactions. In this paper we point out that several commonly used studies of the nuclear enhancement factor fail to account for the spectrally averaged energy loss fraction which ensures that the energy fraction transferred to photons is averaged properly with the spectra of CR species. We present a new calculation of the spectrally averaged energy loss fraction and the nuclear enhancement factor usingmore » the QGSJET-II-04 and EPOS-LHC interaction models.« less
Authors:
 [1] ; ;  [2]
  1. Institutt for fysikk, NTNU, NO-7491 Trondheim (Norway)
  2. Hansen Experimental Physics Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, CA 94305 (United States)
Publication Date:
OSTI Identifier:
22365672
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 789; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASTRONOMY; CERN LHC; COSMIC RADIATION; EMISSION; ENERGY LOSSES; GAMMA RADIATION; HADRONS; INTERACTIONS; INTERSTELLAR SPACE; MEV RANGE; PHOTONS; SPECTRA; TELESCOPES; TEV RANGE