NUCLEAR ENHANCEMENT OF THE PHOTON YIELD IN COSMIC RAY INTERACTIONS

The concept of the nuclear enhancement factor has been used since the beginning of [gamma]-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 [gamma]-ray emission. An acc...

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Bibliographic Details
Published in:The Astrophysical journal 2014-07, Vol.789 (2), p.1-6
Main Authors: Kachelriess, Michael, Moskalenko, Igor V, OSTAPCHENKO, SERGEY S
Format: Article
Language:English
Subjects:
ASTRONOMY
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CERN LHC
COSMIC RADIATION
Cosmic rays
Diffusion
EMISSION
Energy (nuclear)
ENERGY LOSSES
GAMMA RADIATION
HADRONS
INTERACTIONS
INTERSTELLAR SPACE
Mathematical models
MEV RANGE
PHOTONS
SPECTRA
TELESCOPES
TEV RANGE
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Summary:The concept of the nuclear enhancement factor has been used since the beginning of [gamma]-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 [gamma]-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 [gamma]-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 using the QGSJET-II-04 and EPOS-LHC interaction models.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/789/2/136