The faint light in groups and clusters of galaxies

TL;DR

This review summarizes recent advances in the study of intracluster light (ICL) in galaxy groups and clusters, highlighting technological progress, key findings on ICL origins, and its role in understanding dark matter and structure formation.

Contribution

It synthesizes recent observational results and provides a comprehensive overview of ICL properties, origins, and implications for galaxy cluster evolution.

Findings

ICL originates from stars stripped during galaxy interactions

Deep surveys have revealed the faintest ICL components

ICL can be used to map dark matter in clusters

Abstract

The diffuse light that spreads through groups and clusters of galaxies is made of free-floating stars not bound to any galaxy. This is known as the intracluster light (ICL) and holds important clues for understanding the evolution of these large structures. The study of this light has gained traction in the past 20 years thanks to technological and data processing advances that have permitted us to reach unprecedented observational depths. This progress has led to ground-breaking results in the field, such as pinpointing the origin of the ICL and its potential to map dark matter in clusters of galaxies. We now enter an era of deep and wide surveys that promise to uncover the faint Universe as never seen before, adding to our growing understanding of the properties of the ICL and, consequently, of the formation of the largest gravitationally bound structures in the Universe. The goal of this Review is to summarize the most recent results on ICL, synthesizing the current knowledge in the field and providing a global perspective that may benefit future ICL studies.