Truncated Stellar Discs in X-ray Rich Environments

Abstract

We study the dependence of galaxy disc components on environment using a sample of Sloan Digital Sky Survey Data Release 7 galaxies with structural parameters obtained via bulge-disc decompositions. We define two group environments based on X-ray richness at fixed halo mass, with an X-ray rich group sample and an X-ray poor group sample, and compare disc properties of galaxies in these environments to an isolated field population. At low bulge mass, we find evidence for galaxy stellar disc truncation in X-ray rich groups compared to both galaxies in X-ray poor groups and in the isolated field. Additionally, we show that galaxies in X-ray rich groups have smaller disc-to-total mass ratios than their isolated field counterparts. We find that our results are largely independent of group-centric position and halo mass; with the exception that disc truncation is slightly enhanced near the centres of large halos. Our findings demonstrate that galaxy stellar disc properties are sensitive to the X-ray brightness of their host group, more-so than local density parameters, suggesting that IGM-dependent hydrodynamic processes play a role in disc truncation. We suggest that ram-pressure stripping or starvation could be the mechanisms responsible for these results.