The Outer Halos of Very Massive Galaxies: BCGs and their DSC in the Magneticum Simulations

TL;DR

This study uses Magneticum simulations to explore the formation and properties of diffuse stellar components around massive galaxies, successfully matching observed intracluster light distributions and revealing complex dynamics.

Contribution

It provides new insights into the buildup and spatial distribution of the diffuse stellar component in galaxy clusters, aligning simulation results with observations.

Findings

DSC reproduces observed intracluster light distribution and kinematics.

Most halos show a single Sersic profile combining BCG and DSC.

No correlation between BCG and DSC components in halos with two components.

Abstract

Recent hydrodynamic cosmological simulations cover volumes up to Gpc^3 and resolve halos across a wide range of masses and environments, from massive galaxy clusters down to normal galaxies, while following a large variety of physical processes (star formation, chemical enrichment, AGN feedback) to allow a self-consistent comparison to observations at multiple wavelengths. Using the Magneticum simulations, we investigate the buildup of the diffuse stellar component (DSC) around massive galaxies within group and cluster environments. The DSC in our simulations reproduces the spatial distribution of the observed intracluster light (ICL) as well as its kinematic properties remarkably well. For galaxy clusters and groups we find that, although the DSC in almost all cases shows a clear separation from the brightest cluster galaxy (BCG) with regard to its dynamic state, the radial stellar density distribution in many halos is often characterized by a single Sersic profile, representing both the BCG component and the DSC, very much in agreement with current observational results. Interestingly, even in those halos that clearly show two components in both the dynamics and the spatial distribution of the stellar component, no correlation between them is evident.