Does the Galaxy-Halo Connection Vary with Environment?

TL;DR

This study tests the galaxy-halo connection assumption using SDSS data, finding that SubHalo Abundance Matching accurately predicts luminosity and stellar mass functions across environments but struggles with galaxy color dependence, especially for centrals.

Contribution

It provides empirical validation of SHAM predictions for luminosity and mass functions across environments and highlights its limitations in modeling galaxy color-environment relations.

Findings

SHAM accurately predicts GLFs and GSMF dependence on environment.

SHAM fails to reproduce the environmental dependence of galaxy color.

Better agreement for satellite galaxy color than for central galaxies.

Abstract

SubHalo Abundance Matching (SHAM) assumes that one (sub)halo property, such as mass Mvir or peak circular velocity Vpeak, determines properties of the galaxy hosted in each (sub)halo such as its luminosity or stellar mass. This assumption implies that the dependence of Galaxy Luminosity Functions (GLFs) and the Galaxy Stellar Mass Function (GSMF) on environmental density is determined by the corresponding halo density dependence. In this paper, we test this by determining from an SDSS sample the observed dependence with environmental density of the ugriz GLFs and GSMF for all galaxies, and for central and satellite galaxies separately. We then show that the SHAM predictions are in remarkable agreement with these observations, even when the galaxy population is divided between central and satellite galaxies. However, we show that SHAM fails to reproduce the correct dependence between environmental density and g-r color for all galaxies and central galaxies, although it better reproduces the color dependence on environmental density of satellite galaxies.