Strangulation in Galaxy Groups

Abstract

We use a cosmological chemodynamical simulation to study how the group environment impacts the star formation (SF) properties of disk galaxies. The simulated group has a total mass of M ~ 8 × 10 12 Msolar and a total X-ray luminosity of LX ~ 1041 erg s-1. Our simulation suggests that ram pressure is not sufficient in this group to remove the cold disk gas from a Vrot ~ 150 km s-1 galaxy. However, the majority of the hot gas in the galaxy is stripped over a timescale of approximately 1 Gyr. Since the cooling of the hot-gas component provides a source for new cold gas, the stripping of the hot component effectively cuts off the supply of cold gas. This in turn leads to a quenching of SF. The galaxy maintains the disk component after the cold gas is consumed, which may lead to a galaxy similar to an S0. Our self-consistent simulation suggests that this strangulation mechanism works even in low-mass groups, providing an explanation for the lower SF rates in group galaxies relative to galaxies in the field.