On the Origin of Gas-stripping of Galaxies in Group Environments

TL;DR

This study uses simulations to explore how low-mass galaxy groups influence the gas content of satellite galaxies, revealing that external pressure and interactions drive gas stripping, especially around a stellar mass threshold of 10^8 solar masses.

Contribution

It provides new insights into the mechanisms and mass dependence of gas stripping in satellite galaxies within group environments, highlighting the role of external pressure and tidal interactions.

Findings

Gas stripping occurs when external pressure exceeds gravitational restoring force.

A characteristic stellar mass of 10^8 M_sun influences gas removal efficiency.

Tidal interactions can cause significant gas loss, often leading to galaxy disruption.

Abstract

We investigate how low-mass group environments ($M_{\rm vir} \sim 10^{12-13}\,M_{\odot}$) influence the gas content of their satellite galaxies with $M_* > 10^{7}\,M_{\odot}$ using the \NHtwo\ simulation. Many satellite galaxies preserve substantial gas reservoirs, yet show signs of outer gas stripping, reminiscent of jellyfish galaxies in clusters. In contrast, low-mass satellites ($<10^8 \, M_{\odot}$) are largely gas-deficient, and some of them undergo gas removal within their host group by external pressure triggered by either galaxy interactions or ram pressure exerted by the hot intragroup medium. Complete gas removal in these satellite galaxies occurs when the external hydrodynamic pressure exceeds the gravitational restoring force, typically due to stochastic events such as galaxy-galaxy interaction or nearby galactic outflows. The emergence of a characteristic stellar mass of $10^8 \, M_{\odot}$ which determines the efficiency of gas removal in groups, likely reflects the differing scaling relations of external pressure with halo mass and gravitational restoring force with stellar mass. While tidal interactions can be a significant cause of gas loss in satellite galaxies, those severe enough to affect the gas content in the central regions typically lead to the complete disruption of the galaxy. Consequently, gas loss driven by tidal interactions may be underestimated in the studies focusing solely on surviving galaxies. Group environments, where environmental effects are weaker and satellite galaxies tend to have lower restoring forces due to their low masses, exhibit complex manifestations of gas loss that are not seen in more massive environments such as clusters.