Matching the Evolution of the Stellar Mass Function Using Log-Normal Star Formation Histories

Abstract

We show that a model consisting of individual, log-normal star formation histories for a volume-limited sample of z ≈ 0 galaxies reproduces the evolution of the total and quiescent stellar mass functions at z ≲ 2.5 and stellar masses {{M}<SUB>*</SUB>}≥slant {{10}<SUP>10</SUP>} {{M}<SUB>☉ </SUB>}. This model has previously been shown to reproduce the star formation rate/stellar mass relation (SFR-{{M}<SUB>*</SUB>}) over the same interval, is fully consistent with the observed evolution of the cosmic SFR density at z≤slant 8, and entails no explicit “quenching” prescription. We interpret these results/features in the context of other models demonstrating a similar ability to reproduce the evolution of (1) the cosmic SFR density, (2) the total/quiescent stellar mass functions, and (3) the SFR-{{M}<SUB>*</SUB>} relation, proposing that the key difference between modeling approaches is the extent to which they stress/address diversity in the (star-forming) galaxy population. Finally, we suggest that observations revealing the timescale associated with dispersion in SFR({{M}<SUB>*</SUB>}) will help establish which models are the most relevant to galaxy evolution.