| Abstract : | Recent observations suggest that the Circumgalactic Medium (CGM), a gaseous medium surrounding galaxies that extends to scales of the order of the virial radius, consists of gas at various ionization states and temperatures (ranging from cold $10^4$K to hot $10^6$K gas). The origin of the cold phase of the CGM, and its coexistence with the hot phase, has not yet been conclusively established and is crucial for the understanding of galaxy evolution.
Moving through the cluster's potential well, cold ISM gas of a galaxy gets ram-pressure stripped, and is lost to the intracluster medium (ICM), depending on the strength of ram-pressure. We carry out idealised 3D hydrodynamical simulations to study the interaction of a galaxy's interstellar medium (ISM) and CGM with the hot ICM. The interplay between hydrodynamical mixing, radiative cooling and gravitational pull that keeps the gas bound within the ISM, can provide insights on the structure of multiphase CGM/ICM.
Once removed from the galactic disc, the stripped (ISM/CGM) gas starts to mix with the low metallicity hot gas in the ICM via Kelvin-Helmholtz and Rayleigh-Taylor instabilities. This introduces small-scale density perturbations in an otherwise stably stratified atmosphere of the ICM. Buoyant oscillations of these perturbations can potentially excite internal gravity waves. We find that depending on the amplitude of initial density perturbation relative to the background, the excited internal gravity waves either propagate undisturbed or break down into turbulence. In presence of radiative cooling this can be an important mechanism enhancing condensation of the hot gas in the stratified ICM. |
