On the correlation between globular clusters and the distribution of dark matter in galaxy clusters: the case of Abell 2744

TL;DR

This study introduces a statistical method to analyze globular cluster distributions as tracers of dark matter in galaxy clusters, applied to Abell 2744, revealing strong correlations with mass maps and potential for independent mass distribution assessments.

Contribution

The paper presents a novel statistical approach using inhomogeneous spatial Poisson point processes to evaluate GCs as tracers of dark matter in galaxy clusters.

Findings

Bright GCs closely trace the mass distribution in Abell 2744.

GC populations correlate more strongly with mass maps than other galactic components.

Bright Blue GCs align with weak lensing derived mass maps, indicating their utility in mass mapping.

Abstract

Globular clusters (GCs) lie scattered around the inner $40\%$ of the virial radius of galaxy clusters, potentially being excellent tracers of the underlying mass distribution. In this paper, we present a statistical method based on assuming that the location of GCs around a galaxy cluster follows an inhomogenous spatial Poisson point process, and we use this method to assess to which galactic component GCs are better tracers of. We apply the method to the galaxy cluster Abell 2744, and we find that the spatial distribution of bright GCs roughly traces the three main interacting clumps in the galaxy cluster, alongside other galaxies with sizeable GC populations. The GC populations are more closely correlated to the predicted mass maps than any other galactic component (Spearman rank coefficients $>0.7$). A perk of this statistical method is that it allows us to distinguish to which map the agreement is closest to. In particular, we find that the Bright Blue GCs are compatible with the mass map solely derived from weak lensing, suggesting that they can provide complementary and independent information on the mass distribution in galaxy clusters with a similar level of detail to that of weak lensing. This statistical method is available in a public repository, and combined with catalogs of GCs in galaxy clusters at different cosmic epochs, it provides an independent method for investigating the mass distribution in these galactic environments.