Globular Cluster Systems and X-Ray Atmospheres in Galaxies* * Released on 2018 January 8th.

We compare the empirical relationships between the mass of a galaxy’s globular cluster system (GCS) MGCS, the gas mass in the hot X-ray atmosphere MX within a fiducial radius of 5re, the total gravitational mass Mgrav within 5re, and lastly the total halo mass Mh calibrated from weak lensing. We use a sample of 45 early-type galaxies for which both GCS and X-ray data are available; all the galaxies in our sample are relatively high-mass with Mh > 1012M⊙. We find that , similar to the previously known scaling relation . Both components scale much more steeply than the more well known dependence of total stellar mass for luminous galaxies. These results strengthen previous suggestions that feedback had little effect on formation of the GCS. The current data are also used to measure the relative mass fractions of baryonic matter and dark matter within 5re. We find a strikingly uniform mean of with few outliers and an rms scatter of ±0.07. This result is in good agreement with two recent suites of hydrodynamic galaxy formation models.