A Simple Model Linking Galaxy and Dark Matter Evolution
Abstract
We construct a simple phenomenological model for the evolving galaxy population by incorporating predefined baryonic prescriptions into a dark matter hierarchical merger tree. The model is based on the simple gas-regulator model introduced by Lilly et al., coupled with the empirical quenching rules of Peng et al. The simplest model already does quite well in reproducing, without re-adjusting the input parameters, many observables, including the main sequence sSFR-mass relation, the faint end slope of the galaxy mass function, and the shape of the star forming and passive mass functions. Similar to observations and/or the recent phenomenological model of Behroozi et al., which was based on epoch-dependent abundance-matching, our model also qualitatively reproduces the evolution of the main sequence sSFR(z) and SFRD(z) star formation rate density relations, the Ms - Mh stellar-to-halo mass relation, and the SFR - Mh relation. Quantitatively the evolution of sSFR(z) and SFRD(z) is not steep enough, the Ms - Mh relation is not quite peaked enough, and, surprisingly, the ratio of quenched to star forming galaxies around M* is not quite high enough. We show that these deficiencies can simultaneously be solved by ad hoc allowing galaxies to re-ingest some of the gas previously expelled in winds, provided that this is done in a mass-dependent and epoch-dependent way. These allow the model galaxies to reduce an inherent tendency to saturate their star formation efficiency, which emphasizes how efficient galaxies around M* are in converting baryons into stars and highlights the fact that quenching occurs at the point when galaxies are rapidly approaching the maximum possible efficiency of converting baryons into stars.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 2014
- DOI:
- 10.1088/0004-637X/793/1/12
- arXiv:
- arXiv:1401.3162
- Bibcode:
- 2014ApJ...793...12B
- Keywords:
-
- dark matter;
- galaxies: abundances;
- galaxies: evolution;
- galaxies: high-redshift;
- galaxies: luminosity function;
- mass function;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 26 pages, 20 figures, 14 tables, accepted for publication in The Astrophysical Journal