The Mass of the Globular Cluster Systems of Early Type Galaxies as Proxy for the Total Galaxy Mass

Nicholas James, Dong-Woo Kim, Giuseppina Fabbiano, Duncan Forbes, Adebusola Alabi

Published 2018-10-22Version 1

Using globular cluster (GC) 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 (ETG), finding a nearly linear relationship between the two physical parameters. We further investigate this scaling relation in conjunction with the previously known relation between the ISM X-ray luminosity (L_X,GAS) and M_TOT using a sample of 83 ETGs, and confirm that MGCS can be effectively used as a proxy of MTOT. 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 MTOT results in a good agreement around halo masses of 10^12 Mo, but suggest higher star formation efficiency than usually assumed both at the low and at the high halo mass ends. The L_X,GAS - M_TOT relation is far tighter in core than cusp ETGs. This is consistent with previous results, indicating that while MTOT is the most important factor in retaining hot ISM in core ETGs (old, passively evolving stellar systems), secondary (non-gravitational) factors may affect gas retention in cusp ETGs. We find that for a given dark matter mass (MDM), cusp galaxies with higher stellar mass (M_STAR) tend to have higher L_X,GAS. This suggests that stellar feedback could be an important secondary factor for determining the amount of hot ISM retained in low L_X,GAS cusp galaxies.