Revisiting the X-ray–mass scaling relations of early-type galaxies with the mass of their globular cluster systems as a proxy for the total galaxy mass

Using globular cluster kinematics and photometry data, we calibrate the scaling relation between the total galaxy mass (M-TOT, including dark matter) and total globular cluster system mass (M-GCS) in a sample of 30 early-type galaxies (ETGs), confirming a nearly linear relationship between the two physical parameters. Using samples of 83 and 57 ETGs, we investigate this scaling relation in conjunction with the previously known relations between M-TOT and the interstellar medium (ISM) X-ray luminosity and temperature, respectively. We confirm that M-GCS can be effectively used as a proxy of M-TOT. We further find that the L-X,L-GAS-M-TOT relation is far tighter in the subsample of core ETGs when compared to cusp ETGs. In core ETGs (old, passively evolving stellar systems) M-TOT is significantly larger than the total stellar mass M-STAR and the correlation with the hot gas properties is driven by their dark matter mass M-DM. Cusp ETGs typically have lower L-X,L- GAS than core ETGs. In cusp ETGs, for a given M-DM, higher L-X,L- GAS is associated with higher M-STAR, suggesting stellar feedback as an important secondary factor for heating the ISM. Using the M-GCS-M-TOT scaling relations we compare 272 ETGs with previous estimates of the stellar-to-halo-mass relation of galaxies. Our model-independent estimate of M-TOT results in a good agreement around halo masses of 10(12)M(circle dot), but suggests higher star formation efficiency than usually assumed both at the low- and at the high-halo-mass ends.