Dark matter searches by the planned gamma-ray telescope GAMMA-400. (arXiv:2005.09032v2 [astro-ph.HE] UPDATED)

Dark matter searches by the planned gamma-ray telescope GAMMA-400. (arXiv:2005.09032v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Egorov_A/0/1/0/all/0/1">Andrey E. Egorov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Topchiev_N/0/1/0/all/0/1">Nikolay P. Topchiev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galper_A/0/1/0/all/0/1">Arkadiy M. Galper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Dalkarov_O/0/1/0/all/0/1">Oleg D. Dalkarov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Leonov_A/0/1/0/all/0/1">Alexey A. Leonov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Suchkov_S/0/1/0/all/0/1">Sergey I. Suchkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yurkin_Y/0/1/0/all/0/1">Yuriy T. Yurkin</a>

Our paper reviews the planned space-based gamma-ray telescope GAMMA-400 and
evaluates in details its opportunities in the field of dark matter (DM)
indirect searches. We estimated GAMMA-400 mean sensitivity to the diphoton DM
annihilation cross section in the Galactic center for DM particle masses in the
range of 1-500 GeV. We obtained the sensitivity gain at least by 1.2-1.5 times
(depending on DM particle mass) with respect to the expected constraints from
12 years of observations by Fermi-LAT for the case of Einasto DM density
profile. The joint analysis of the data from both telescopes may yield the gain
up to 1.8-2.3 times. Thus the sensitivity reaches the level of annihilation
cross section $langle sigma v
rangle_{gammagamma}(m_chi=100~mbox{GeV})approx 10^{-28}$ cm$^3$/s. This
will allow us to test the hypothesized narrow lines predicted by specific DM
models, particularly the recently proposed pseudo-Goldstone boson DM model. We
also considered the decaying DM – in this case the joint analysis may yield the
sensitivity gain up to 1.1-2.0 times reaching the level of DM lifetime
$tau_{gammanu}(m_chi=100~mbox{GeV}) approx 2cdot 10^{29}$ s. We
estimated the GAMMA-400 sensitivity to axion-like particle (ALP) parameters by
a potential observation of the supernova explosion in the Local Group. This is
very sensitive probe of ALPs reaching the level of ALP-photon coupling constant
$g_{agamma} sim 10^{-13}~mbox{GeV}^{-1}$ for ALP masses $m_a lesssim 1$
neV. We also calculated the sensitivity to ALPs by constraining the modulations
in the spectra of the Galactic gamma-ray pulsars due to possible ALP-photon
conversion. GAMMA-400 is expected to be more sensitive than the CAST helioscope
for ALP masses $m_a approx (1-10)$ neV reaching $g_{agamma}^{min} approx
2cdot 10^{-11}~mbox{GeV}^{-1}$. Other potentially interesting targets and
candidates are briefly considered too.

Our paper reviews the planned space-based gamma-ray telescope GAMMA-400 and
evaluates in details its opportunities in the field of dark matter (DM)
indirect searches. We estimated GAMMA-400 mean sensitivity to the diphoton DM
annihilation cross section in the Galactic center for DM particle masses in the
range of 1-500 GeV. We obtained the sensitivity gain at least by 1.2-1.5 times
(depending on DM particle mass) with respect to the expected constraints from
12 years of observations by Fermi-LAT for the case of Einasto DM density
profile. The joint analysis of the data from both telescopes may yield the gain
up to 1.8-2.3 times. Thus the sensitivity reaches the level of annihilation
cross section $langle sigma v
rangle_{gammagamma}(m_chi=100~mbox{GeV})approx 10^{-28}$ cm$^3$/s. This
will allow us to test the hypothesized narrow lines predicted by specific DM
models, particularly the recently proposed pseudo-Goldstone boson DM model. We
also considered the decaying DM – in this case the joint analysis may yield the
sensitivity gain up to 1.1-2.0 times reaching the level of DM lifetime
$tau_{gammanu}(m_chi=100~mbox{GeV}) approx 2cdot 10^{29}$ s. We
estimated the GAMMA-400 sensitivity to axion-like particle (ALP) parameters by
a potential observation of the supernova explosion in the Local Group. This is
very sensitive probe of ALPs reaching the level of ALP-photon coupling constant
$g_{agamma} sim 10^{-13}~mbox{GeV}^{-1}$ for ALP masses $m_a lesssim 1$
neV. We also calculated the sensitivity to ALPs by constraining the modulations
in the spectra of the Galactic gamma-ray pulsars due to possible ALP-photon
conversion. GAMMA-400 is expected to be more sensitive than the CAST helioscope
for ALP masses $m_a approx (1-10)$ neV reaching $g_{agamma}^{min} approx
2cdot 10^{-11}~mbox{GeV}^{-1}$. Other potentially interesting targets and
candidates are briefly considered too.

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