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arXiv · 1810.09475

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

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

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), 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 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,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 have typically lower LX,GAS than core ETGs. In cusp ETGs, for a given M_DM, higher L_X,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 Mo, but suggest higher star formation efficiency than usually assumed both at the low and at the high halo mass ends.

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Dong-Woo Kim, Nicholas James, Giuseppina Fabbiano, Duncan Forbes, Adebusola Alabi. 2018-10-22. 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. https://doi.org/10.1093/mnras/stz1522

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