Cosmic Environment as the Primary Driver of Dwarf Satellite Statistics

TL;DR

This study uses simulations to analyze how the cosmic environment influences dwarf satellite galaxy populations, revealing environment-dependent variations in abundance, distribution, and evolution from early times to the present.

Contribution

It provides a comprehensive analysis of satellite galaxy statistics across different environments and cosmic times within the b1CDM framework, highlighting the primary role of cosmic environment.

Findings

Dense environments suppress satellite populations compared to voids.

Satellite abundance correlates strongly with host stellar and bulge mass.

Radial profiles vary with environment, showing central concentration in voids and flattened distributions in clusters.

Abstract

Context: Satellite dwarf galaxies provide key constraints on galaxy formation and evolution, since their abundance and spatial distribution reflect both the host properties and the large-scale environment. Aims: This study quantifies the dependence of satellite populations on the host stellar mass, morphology, and star formation activity across different environments, and traces their evolution with cosmic time within the $\Lambda$CDM framework. Methods: The Millennium-II simulation combined with the G11 semi-analytic model is used to construct consistent samples of host galaxies brighter than $M_{r}<-16$ and their satellites ($M_{\ast}\geq 3\times10^{5}\,M_{\odot}$, $M_{r}<-9$) within the virial radius. Satellite abundance and radial profiles are analysed in cluster, group, and void environments, and their evolution is traced from $z=2$ to $z=0$ across three host stellar mass bins. Results: Satellite abundance is correlated strongly with host stellar and bulge mass, whereas host morphology has little independent effect once stellar mass is accounted for. Dense environments suppress satellite populations relative to voids. Correlations between satellite abundance, specific star formation rate, and disk scale length become evident only in groups and clusters. At $z=0$, radial profiles show strong central concentrations in voids, flattened distributions in clusters, and intermediate trends in groups. Their redshift evolution reveals progressive flattening for low- and intermediate-mass hosts in dense environments, stability for massive hosts, and increasing central concentration in voids. The cosmic evolution of satellite abundance further highlights distinct pathways: gradual accumulation in voids, mass-dependent trends in groups, and strong late-time suppression in clusters.