Towards a comprehensive knowledge of the star cluster population in the Small Magellanic Cloud

TL;DR

This study critically assesses the star cluster population in the Small Magellanic Cloud, revealing that previous estimates are likely overestimated due to detection biases and highlighting the spatial variation and dissolution processes of clusters.

Contribution

It provides the first analysis showing how cluster dissolution rates vary spatially and depend on galaxy mass concentration and external tidal forces.

Findings

Previous cluster counts are likely overestimated.

Cluster frequency varies spatially, influenced by galaxy interactions.

Dissolution rates depend on local galaxy mass and external forces.

Abstract

The Small Magellanic Cloud (SMC) has recently been found to harbour more than two hundred per cent increase of its known cluster population. We provide here with solid evidence that such an unprecedented number of clusters could be largely overestimated. On the one hand, the fully-automatic procedure used to identify such an enormous cluster candidate sample did not recover ~ 50 per cent, in average, of the known relatively bright clusters located in the SMC main body. On the other hand, the number of new cluster candidates per time unit as a function of time results noticeably different to the intrinsic SMC cluster frequency (CF), which should not be the case if these new detections were genuine physical systems. We additionally found that the SMC CF varies spatially, in such a way that it resembles an outside-in process coupled with the effects of a relatively recent interaction with the Large Magellanic Cloud. By assuming that clusters and field stars share the same formation history, we showed for the first time that the cluster dissolution rate also depends on the position in the galaxy. The cluster dissolution results higher as the concentration of galaxy mass increases or external tidal forces are present.