Intracluster light: a luminous tracer for dark matter in clusters of galaxies

TL;DR

This study demonstrates that intracluster light (ICL) closely traces the overall dark matter distribution in galaxy clusters, offering a new method to map dark matter using deep imaging data.

Contribution

The paper shows that ICL can serve as an accurate luminous tracer of dark matter in galaxy clusters, validated through comparison with gravitational lensing models.

Findings

ICL distribution closely matches dark matter distribution (MHD~25 kpc).

ICL can be used to explore dark matter in clusters with deep imaging.

Strong correlation between ICL and dark matter shapes.

Abstract

The bulk of stars in galaxy clusters are confined within their constituent galaxies. Those stars do not trace the extended distribution of dark matter well as they are located in the central regions of the cluster's dark matter sub-halos. A small fraction of stars is expected, however, to follow the global dark matter shape of the cluster. These are the stars whose extended spatial distribution results from the merging activity of galaxies and form the intracluster light (ICL). In this work, we compare the bi-dimensional distribution of dark matter in massive galaxy clusters (as traced by gravitational lensing models) with the distribution of the ICL. To do that, we use the superb data from the Hubble Frontier Fields Initiative. Using the Modified Hausdorff distance (MHD) as a way of quantifying the similarities between the mass and ICL distributions, we find an excellent agreement (MHD~25 kpc) between the two components. This result shows that the ICL exquisitely follows the global dark matter distribution, providing an accurate luminous tracer of dark matter. This finding opens up the possibility of exploring the distribution of dark matter in galaxy clusters in detail using only deep imaging observations.