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

Here we utilize recent measures of galaxy total dynamical mass and X-ray gas luminosities (L-X,L- Gas) for a sample of 29 massive early-type galaxies from the SLUGGS survey to probe LX, 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 cold dark matter simulations. We find a strong linear relationship between L-X,L- Gas and galaxy dynamical mass within 5R(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 haloes so that L-X,L- 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,L- Gas.