1609.04398
Star formation quenching timescale of central galaxies in a hierarchical universe
Hahn, Tinker, Wetzel
Central galaxies make up the majority of the galaxy population, including the majority of the quiescent population at M*>1e10 Msun. Thus, the mechanisms(s) responsible for quenching central galaxies plays a crucial rote in galaxy evolution as a whole. Combine a high resolution cosmo N-body sim with observed evolutionary trends of the "star formation main sequence," quiescent fraction, and stellar mass function at z<1 to construct a model that statistically tracks the SFHs and quenching of central galaxies. Comparing this model to the distribution of central galaxy star formation rates in a group catalog of SDSS DR7, constrain the timescales over which physical processes cease SF in central galaxies. Over the stellar mass range 1e9.5 to 1e11 Msun, infer quenching e-folding times that span 1.5 to 0.5 Gyr with more massive central galaxies quenching faster. For M*=1e10.5 Msun, this implies a total migration time of ~4 Gyrs from the SF MS to quiescence. Compared to satellites, central galaxies take ~2 Gyrs long er to quench their SF, suggesting that different mechanisms are responsible for quenching centrals versus satellites. The central galaxy quenching timescale inferred provides key constraints for proposed SF quenching mechanisms. The timescale is generally consistent with gas depletion timescales predicted by quenching through strangulation. However, the exact physical mechanism(s) responsible for this still remain unclear.
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