PoS - Proceedings of Science
Volume 395 - 37th International Cosmic Ray Conference (ICRC2021) - GAD - Gamma Ray Direct
High Energy Gamma-Ray Emission from the Coma Cluster Region: Deep Morphological and Spectral Studies.
D. Zargaryan*, V. Baghmanyan, F. Aharonian, J. Mackey, S. Casanova and R. Yang
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Pre-published on: July 06, 2021
Published on: March 18, 2022
The Coma galaxy cluster is one of the largest gravitationally-bound astrophysical structures in the local Universe, with a linear size of more than 2 Mpc and a z=0.023 distance. The relatively high intracluster density and the high-velocity accretion shocks within the cluster make it a possible source of high energy (HE) $\gamma$-ray emission. Using 12.3 years of Fermi-LAT Pass 8 data between 100 MeV and 1 TeV energies, we report the detection of HE diffuse $\gamma$-ray emission from the direction of the Coma cluster with $5.4 \sigma$ extension significance and R$_{68}$ = 0.82$^{\circ}$ extension described with a homogeneous disk model. The corresponding $\gamma$-ray spectrum extends up to $\sim50$ GeV with power-law spectral index $\Gamma = 2.23 \pm 0.11 $ and energy flux of $(3.48\pm0.68)\times10^{-12}$ erg cm$^{-2}$ s$^{-1}$. Furthermore, three point-like structures with power-law indexes of $2.44\pm0.28$, $2.56\pm0.32$, and $1.99\pm0.30$ show improvement in the fit by $\mathrm{\Delta_{AIC}}=7.2$ indicating more $\gamma$-ray sources in the region.
DOI: https://doi.org/10.22323/1.395.0582
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