Modelling of propagation of very-high-energy gamma rays with CRbeam code. Comparison with CRPropa and ELMAG codes. (arXiv:2201.03996v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kalashev_O/0/1/0/all/0/1">O.Kalashev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Korochkin_A/0/1/0/all/0/1">A.Korochkin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Neronov_A/0/1/0/all/0/1">A.Neronov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Semikoz_D/0/1/0/all/0/1">D.Semikoz</a>
Very-high-energy gamma rays produce electron positron pairs in interactions
with low-energy photons of extragalactic background light during propagation
through the intergalactic medium. The electron-positron pairs generate
secondary gamma rays detectable by gamma-ray telescopes. This secondary
emission can be used to detect Inter-Galactic Magnetic Fields (IGMF) in the
voids of Large Scale Structure. New gamma-ray observatory, Cherenkov Telescope
Array (CTA), will provide an increase of sensitivity for detection of these
secondary gamma-ray emission and enable measurement of its properties for
sources at cosmological distances. Interpretation of the CTA data including
detection of IGMF and study of it’s properties and origin will require
precision modelling of the primary and secondary gamma-ray fluxes. We asses the
precision of the modelling of the secondary gamma-ray emission using model
calculations with publicly available Monte-Carlo codes CRPropa and ELMAG and
compare their predictions with theoretical expectations and with model
calculations of a newly developed CRbeam code. We find that model predictions
of different codes differ by up to 50% for low-redshift sources, with
discrepancies increasing up to order-of-magnitude level with the increasing
source redshifts. We identify the origin of these discrepancies and argue that
the new CRbeam code provides reliable predictions for spectral, timing and
imaging properties of the secondary gamma-ray signal and can be used to study
gamma-ray sources and IGMF with precision relevant for the prospective CTA
study of the effects of gamma-ray propagation through the intergalactic medium.
Very-high-energy gamma rays produce electron positron pairs in interactions
with low-energy photons of extragalactic background light during propagation
through the intergalactic medium. The electron-positron pairs generate
secondary gamma rays detectable by gamma-ray telescopes. This secondary
emission can be used to detect Inter-Galactic Magnetic Fields (IGMF) in the
voids of Large Scale Structure. New gamma-ray observatory, Cherenkov Telescope
Array (CTA), will provide an increase of sensitivity for detection of these
secondary gamma-ray emission and enable measurement of its properties for
sources at cosmological distances. Interpretation of the CTA data including
detection of IGMF and study of it’s properties and origin will require
precision modelling of the primary and secondary gamma-ray fluxes. We asses the
precision of the modelling of the secondary gamma-ray emission using model
calculations with publicly available Monte-Carlo codes CRPropa and ELMAG and
compare their predictions with theoretical expectations and with model
calculations of a newly developed CRbeam code. We find that model predictions
of different codes differ by up to 50% for low-redshift sources, with
discrepancies increasing up to order-of-magnitude level with the increasing
source redshifts. We identify the origin of these discrepancies and argue that
the new CRbeam code provides reliable predictions for spectral, timing and
imaging properties of the secondary gamma-ray signal and can be used to study
gamma-ray sources and IGMF with precision relevant for the prospective CTA
study of the effects of gamma-ray propagation through the intergalactic medium.
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