Effects of large-scale environment on the assembly history of central galaxies

TL;DR

This study investigates whether large-scale environment influences the assembly history of central galaxies, finding minimal impact on stellar mass growth but slight effects on star formation rates, with implications for future observations.

Contribution

The paper demonstrates that, contrary to halo formation times, the stellar mass growth of central galaxies is largely unaffected by large-scale environment in a semi-analytic model.

Findings

Stellar mass growth of central galaxies is insensitive to large-scale environment.

Small effects of assembly bias on star formation rates are present but difficult to detect.

Future surveys may test these model predictions with more sensitive data.

Abstract

We examine whether large-scale environment affects the mass assembly history of their central galaxies. To facilitate this, we constructed dark matter halo merger trees from a cosmological N-body simulation and calculated the formation and evolution of galaxies using a semi-analytic method. We confirm earlier results that smaller halos show a notable difference in formation time with a mild dependence on large-scale environment. However, using a semi-analytic model, we found that on average the growth rate of the stellar mass of central galaxies is largely insensitive to large-scale environment. Although our results show that the star formation rate (SFR) and the stellar mass of central galaxies in smaller halos are slightly affected by the assembly bias of halos, those galaxies are faint, and the difference in the SFR is minute, and therefore it is challenging to detect it in real galaxies given the current observational accuracy. Future galaxy surveys, such as the BigBOSS experiment and the Large Synoptic Survey Telescope, which are expected to provide observational data for fainter objects, will provide a chance to test our model predictions.