An investigation of gamma-ray production by hadronic interaction between cosmic-ray protons and the CGM
This video briefly summarizes Roy & Nath 2022 . In this paper, we discuss the production of gamma-rays from cosmic rays in the circumgalactic medium (CGM) of Andromeda (M31) in light of the recent detection of gamma-rays from an annular region of ~5.5-120 kpc away from the M31 disc. We consider the cosmic rays accelerated as a result of the star formation in the M31 disk and in-situ in shocks, which are lifted to the CGM by advection due to outflow and CR diffusion. We investigate this scenario by the production of gamma-rays via hadronic interaction between cosmic-ray protons and CGM gas with the help of numerical two-fluid (thermal + cosmic rays) hydrodynamical simulation code PLUTO. We find that a combination of these mechanisms, that are related to the star formation processes in M31 in the last 1 Gyr, along with diffusion and hadronic interaction, can explain the observed flux from the CGM of M31.