The size function of massive satellites from the $R_e-R_h$ and $M_{star}-M_h$ relations: constraining the role of environment

TL;DR

This study demonstrates that a semi-empirical model linking galaxy sizes to halo properties can accurately reproduce the size distributions of massive satellite galaxies and their dependence on environment, without additional calibration.

Contribution

It shows that the same size-halo relation model explains satellite galaxy sizes and their weak dependence on host halo mass, extending previous work on central galaxies.

Findings

Model reproduces size function of quiescent satellite MGs in SDSS.

Model explains weak size dependence on host halo mass.

Predicted formation times of satellite lenticulars relative to infall.

Abstract

In previous work we showed that a semi-empirical model in which galaxies in host dark matter haloes are assigned stellar masses via a stellar mass-halo mass (SMHM) relation and sizes ($R_e$) via a linear and tight $R_e-R_h$ relation, can faithfully reproduce the size function of local SDSS central galaxies and the strong size evolution of massive galaxies (MGs, $M_{\rm star}>10^{11.2}M_\odot$). In this third paper of the series, we focus on the population of satellite MGs. We find that without any additional calibration and irrespective of the exact SMHM relation, fraction of quenched galaxies or level of stellar stripping, the same model is able to reproduce the local size function of quiescent satellite MGs in SDSS. In addition, the same model can reproduce the puzzling weak dependence of mean size on host halo mass for both central and satellite galaxies. The model also matches the size function of starforming satellite MGs, after assuming that some of them transform into massive lenticulars in a few Gyr after infalling in the group/cluster environment. However, the vast majority of satellite lenticulars is predicted to form before infall. The $R_e-R_h$ appears to be fundamental to connect galaxies and their host haloes.