The progenitors of the intra-cluster light and intra-cluster globular clusters in galaxy groups and clusters

TL;DR

This study uses cosmological simulations to analyze the origins and properties of intra-cluster light and globular clusters, revealing their assembly history and relation to galaxy accretion in groups and clusters.

Contribution

It provides new insights into the formation of ICL and ICGC, linking their properties to the mass and type of accreted galaxies using the IllustrisTNG50 simulation.

Findings

ICL mass is 10-20% of central galaxy mass.

Half of the ICL originates from galaxies with stellar mass 10^10-10^11 M_sun.

Dwarf galaxy accretion influences ICL metallicity and distribution.

Abstract

We use the IllustrisTNG50 cosmological hydrodynamical simulation, complemented by a catalog of tagged globular clusters, to investigate the properties and build up of two extended luminous components: the intra-cluster light (ICL) and the intra-cluster globular clusters (ICGC). We select the 39 most massive groups and clusters in the box, spanning the range of virial masses $5 \times 10^{12} < \rm M_{200}/\rm M_{\odot} < 2 \times 10^{14}$. We find good agreement between predictions from the simulations and current observational estimates of the fraction of mass in the ICL and its radial extension. The stellar mass of the ICL is only $\sim10\%-20\%$ of the stellar mass in the central galaxy but encodes useful information on the assembly history of the group or cluster. About half the ICL in all our systems is brought in by galaxies in a narrow stellar mass range, $M_*=10^{10}-10^{11}$ $\rm M_{\odot}$. However, the contribution of low-mass galaxies ($M_*<10^{10}$ $\rm M_{\odot}$) to the build-up of the ICL varies broadly from system to system, $\sim 5\%-45\%$, a feature that might be recovered from the observable properties of the ICL at $z=0$. At fixed virial mass, systems where the accretion of dwarf galaxies plays an important role have shallower metallicity profiles, less metal content and a lower stellar mass in the ICL than systems where the main contributors are more massive galaxies. We show that intra-cluster GCs are also good tracers of this history, representing a valuable alternative when diffuse light is not detectable.