Constraints on the Evolution of the Galaxy Stellar Mass Function I: Role of Star Formation, Mergers and Stellar Stripping

TL;DR

This study models the evolution of the galaxy stellar mass function by integrating star formation, mergers, and stellar stripping, showing the importance of a mass-dependent SFR-$M_*$ relation and the effects of mergers and stripping on massive galaxies.

Contribution

It introduces a model combining subhalo abundance matching with merger trees, considering stellar stripping, to better match observed galaxy mass functions over cosmic time.

Findings

Mass-dependent SFR-$M_*$ relation aligns better with observed SMF evolution.

Both mergers and stellar stripping significantly influence the high-mass end of the SMF.

Model predictions agree with SDSS data, especially when stellar stripping is included.

Abstract

We study the connection between the observed star formation rate-stellar mass (SFR-$M_*$) relation and the evolution of the stellar mass function (SMF) by means of a Subhalo Abundance Matching technique coupled to merger trees extracted from a N-body simulation. Our approach, which considers both galaxy mergers and stellar stripping, is to force the model to match the observed SMF at redshift $z>2$, and let it evolve down to the present time according to the observed (SFR-$M_*$) relation. In this study, we use two different sets of SMFs and two SFR-$M_*$ relations: a simple power law and a relation with a mass-dependent slope. Our analysis shows that the evolution of the SMF is more consistent with a SFR-$M_*$ relation with a mass-dependent slope, in agreement with predictions from other models of galaxy evolution and recent observations. In order to fully and realistically describe the evolution of the SMF, both mergers and stellar stripping must be considered, and we find that both have almost equal effects on the evolution of SMF at the massive end. Taking into account the systematic uncertainties in the observed data, the high-mass end of the SMF obtained by considering stellar stripping results in good agreement with recent observational data from the Sloan Digital Sky Survey (SDSS). At $\log M_* < 11.2$, our prediction at z=0.1 is close to \citet{li-white09} data, but the high-mass end ($\log M_* > 11.2$) is in better agreement with \citet{dsouza15} data which account for more massive galaxies.