On the Origin of Intracluster Light based on the High-resolution Simulation, NewCluster

TL;DR

This study uses high-resolution simulations to trace the origin and properties of intracluster light, revealing its main source as satellite galaxies and linking its characteristics to cluster assembly history.

Contribution

It provides a detailed, particle-level analysis of ICL origins and properties using the NewCluster simulation, offering a new quantitative approach to study cluster assembly.

Findings

Most ICL originates from satellite galaxies.

Preprocessed component matches dark matter density profile.

Satellite stripping depends on infall time and pericenter distance.

Abstract

Intracluster light (ICL) is a key component of galaxy clusters, with the potential to trace their dynamical assembly histories and the underlying dark matter distribution. Despite these prospects, its faint nature makes a consensus on its origin or population properties difficult to achieve, both in observations and simulations. In the hope of finding a breakthrough, we utilize the ongoing high-resolution cluster simulation, NewCluster. By classifying billions of particles in and around the cluster with a rigorous tracking procedure, we find that the majority of the ICL originates from satellites, including surviving and disrupted galaxies. Another notable finding is that the preprocessed component follows the density profile of dark matter better than the other components and has distinctive properties: old age, low metallicity, and enhanced $\alpha$-element abundance. We further investigate the orbital dynamics, and our results demonstrate that the stripped fraction of satellites is primarily determined by the time since infall and the pericenter distance. By linking the demographic, chemical, and orbital properties of ICL stars to their origins, this work proposes a quantitative approach for tracing the assembly history of galaxy clusters from the ICL.