The fate of the gaseous discs of galaxies that fall into clusters

Abstract

Galaxy clusters are known to induce gas loss in infalling galaxies due to the ram pressure exerted by the intracluster medium over their gas content. In this paper, we investigate this process through a set of simulations of MilkyWay like galaxies falling inside idealized clusters of 1014 and 1015 M⊙, containing a cool core or not, using the adaptive mesh refinement code RAMSES. We use these simulations to constrain how much of the initial mass contained in the gaseous disc of the galaxy will be converted into stars and how much of it will be lost, after a single crossing of the entire cluster. We find that, if the galaxy reaches the central region of a cool-core cluster, it is expected to lose all its gas, independently of its entry conditions and of the cluster's mass. On the other hand, it is expected to never lose all its gas after crossing a cluster without a cool core just once. Before reaching the centre of the cluster, the star formation rate (SFR) of the galaxy is always enhanced, by a factor of 1.5-3. If the galaxy crosses the cluster without being completely stripped, its final amount of gas is on average two times smaller after crossing the 1015 M⊙ cluster, relative to the 1014 M⊙ cluster. This is reflected in the final SFR of the galaxy, which is also two times smaller in the former, ranging from 0.5 to 1 M⊙ yr-1, compared to 1-2 M⊙ yr-1 for the latter.