Is diffuse intracluster light a good tracer of the galaxy cluster matter distribution?

TL;DR

This study investigates whether diffuse intracluster light can reliably trace the distribution of matter in galaxy clusters, finding it correlates well with total mass but is not a perfect radial indicator.

Contribution

The paper combines observational data from DES and simulations to assess the relationship between diffuse light and cluster matter distribution, revealing its potential as a mass indicator.

Findings

Diffuse light shows a universal radial dependence after scaling by cluster radius.

Diffuse light correlates strongly with total cluster mass, outperforming satellite galaxy stellar mass.

No conclusive evidence that diffuse light precisely traces the matter distribution radially.

Abstract

We explore the relation between diffuse intracluster light (central galaxy included) and the galaxy cluster (baryonic and dark) matter distribution using a sample of 528 clusters at $0.2\leq z \leq 0.35$ found in the Dark Energy Survey (DES) Year 1 data. The surface brightness of the diffuse light shows an increasing dependence on cluster total mass at larger radius, and appears to be self-similar with a universal radial dependence after scaling by cluster radius. We also compare the diffuse light radial profiles to the cluster (baryonic and dark) matter distribution measured through weak lensing and find them to be comparable. The IllustrisTNG galaxy formation simulation, TNG300, offers further insight into the connection between diffuse stellar mass and cluster matter distributions -- the simulation radial profile of the diffuse stellar component does not have a similar slope with the total cluster matter content, although that of the cluster satellite galaxies does. Regardless of the radial trends, the amount of diffuse stellar mass has a low-scatter scaling relation with cluster's total mass in the simulation, out-performing the total stellar mass of cluster satellite galaxies. We conclude that there is no consistent evidence yet on whether or not diffuse light is a faithful radial tracer of the cluster matter distribution. Nevertheless, both observational and simulation results reveal that diffuse light is an excellent indicator of the cluster's total mass.