Pair-production opacity at high and very-high gamma-ray energies

Horns, D.; Meyer, M.

Report/Contribution to a conference proceedings/Contribution to a book

PUBDB-2018-02789

Pair-production opacity at high and very-high gamma-ray energies

Horns, D. (Corresponding author) ; Meyer, M.

2013
Verlag Deutsches Elektronen-Synchrotron Hamburg
ISBN: 978-3-935702-83-6

Horns, D. "Pair-production opacity at high and very-high gamma-ray energies" in Proceedings, 9th Patras Workshop on Axions, WIMPs and WISPs (AXION-WIMP 2013) / Oberlack, Uwe, Sissol, Pierre (eds.), 2013 ; AXION-WIMP 2013 : 9th Patras Workshop on Axions, WIMPs and WISPs , 2013-06-23 - 2013-06-28, Mainz
9th Patras Workshop on Axions, WIMPs and WISPs, AXION-WIMP 2013, Mainz, Germany, 24 Jun 2013 - 28 Jun 2013 Hamburg : Verlag Deutsches Elektronen-Synchrotron, DESY-PROC 77-80 (2013) [10.3204/DESY-PROC-2013-04/horns_dieter]

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Please use a persistent id in citations: doi:10.3204/DESY-PROC-2013-04/horns_dieter

Report No.: DESY-PROC-2013-04

Abstract: The propagation of high energy (HE,E$_γ >$ 100 MeV) and very high-energy gammarays (VHE, E$_γ >$ 100 GeV) in the extra-galactic photon field leads to pair- production and consequently energy-and distance-dependent attenuation of the primary intensity. The spectroscopy of an increasing number of extra-galactic objects at HE and VHE energies has demonstrated indeed the presence of such an attenuation which in turn has been used to constrain the photon density in the medium. At large optical depth $(\tau\gtrsim 2)$ potential modifications of pair-production due to competing but rare processes (as, e.g., the presence of sub-neV axion- like particle) may be found. Indications for a pair-production anomaly have previously been found with VHE-spectra. Here, we present further indications (at the level of 3.68 $σ$) for a reduced optical depth at high energies from an analysis of Fermi-LAT data.

Keyword(s): Hypothetisches Teilchen

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