# Smaller stellar disc scale lengths in rich environments

## TL;DR

This study finds that stellar disc sizes are smaller in X-ray rich galaxy groups, indicating environmental effects like ram-pressure stripping influence galaxy structure beyond isolated conditions.

## Contribution

It demonstrates a clear dependence of stellar disc scale lengths on X-ray brightness of galaxy groups, highlighting environmental impact on galaxy morphology.

## Key findings

- Disc scale lengths are smaller in X-ray rich groups at low bulge mass.
- Smaller disc sizes are observed in X-ray rich environments across different galaxy types.
- Results suggest hydrodynamic processes affect galaxy disc sizes in dense environments.

## Abstract

We investigate the dependence of stellar disc scale lengths on environment for a sample of Sloan Digital Sky Survey Data Release 7 galaxies with published photometric bulge-disc decompositions. We compare disc scale lengths at fixed bulge mass for galaxies in an isolated field environment to galaxies in X-ray rich and X-ray poor groups. At low bulge mass, stellar disc scale lengths in X-ray rich groups are smaller compared to discs in both X-ray poor groups and in isolated field environments. This decrease in disc scale length is largely independent of halo mass, though shows some dependence on group-centric distance. We also find that stellar disc scale lengths are smaller in X-ray rich environments for a subset of star-forming galaxies and for galaxies of different morphological types. We note that disc scale lengths of low mass galaxies are known to have large systematic uncertainties, however we focus on differences between samples with the same measurement biases. Our results show that stellar disc scale lengths depend on X-ray brightness, a tracer of IGM density, suggesting a role for hydrodynamic processes such as ram-pressure stripping and/or starvation.