Modeling the Dependence of Galaxy Quenching on Stellar, Baryonic and Halo Mass in the ECO Survey
Constraining the connection between the galaxy properties and the dark matter halos they reside in is a powerful tool for understanding the processes responsible for galaxy formation. While the stellar-to-halo mass relation (SHMR) is one such well-studied connection, there is little consensus on the difference between the SHMRs of red and blue galaxies. The baryonic-to-halo mass relation (BHMR) and its conditional dependence on galaxy colour is even less studied. In this paper, we adopt an empirical forward- modeling mock-based approach to constrain a parameterized SHMR/BHMR model along with three types of quenching models, each employing a different driver of quenching: stellar, baryonic or halo mass. We use mass functions, galaxy blue fractions, and satellite kinematics as constraints measured directly from the ECO survey. Based on our model fits, we identify the mass scale that divides predominantly star- forming galaxies from the quenched population to be ∼ 10^10.2 h^(−2)M⊙ in stellar/baryonic mass or ∼ 10^11.8 h^(−2)M⊙ in halo mass. Moreover, we find that the quenched fraction of galaxies grows from 10% to 90% over ∼1.5 dex in mass. We find that the model where quenching depends on stellar mass provides the best fit to our data, while the halo-driven quenching model is a close second. As a result, we are not able to conclusively detect a dependence of the SHMR on galaxy colour. Finally, we compare our empirical results to predictions from galaxy formation models and show large discrepancies in the quenching fractions of both central and satellite galaxies.
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