The SLUGGS Survey: revisiting the correlation between X-ray luminosity and total mass of massive early-type galaxies

TL;DR

This study examines the relationship between X-ray gas luminosity and galaxy mass in massive early-type galaxies, confirming a strong correlation consistent with cosmological simulations and highlighting the role of dark matter halo potential and AGN heating.

Contribution

It provides new observational evidence linking X-ray luminosity to galaxy mass and compares these findings with predictions from $ abla$CDM simulations, emphasizing the impact of dark matter halos and AGN activity.

Findings

L$_{X,Gas}$ correlates strongly with dynamical mass within 5 R$_e$

Gas heating is primarily due to dark matter halo potential

AGN heating has a secondary but significant role

Abstract

Here we utilise recent measures of galaxy total dynamical mass and X-ray gas luminosities (L$_{X,Gas}$) for a sample of 29 massive early-type galaxies from the SLUGGS survey to probe L$_{X,Gas}$--mass scaling relations. In particular, we investigate scalings with stellar mass, dynamical mass within 5 effective radii (R$_e$) and total virial mass. We also compare these relations with predictions from $\Lambda$CDM simulations. We find a strong linear relationship between L$_{X,Gas}$ and galaxy dynamical mass within 5 R$_e$, which is consistent with the recent cosmological simulations of Choi et al. that incorporate mechanical heating from AGN. We conclude that the gas surrounding massive early-type galaxies was shock heated as it fell into collapsing dark matter halos so that L$_{X,Gas}$ is primarily driven by the depth of a galaxy's potential well. Heating by an AGN plays an important secondary role in determining L$_{X,Gas}$.