Sizing the star cluster population of the Large Magellanic Cloud

TL;DR

This study reevaluates the star cluster population in the Large Magellanic Cloud, concluding that previous claims of a much larger population are likely due to false detections and overdensities, reaffirming the known cluster count.

Contribution

The paper critically reassesses the LMC cluster catalog, highlighting the overestimation issues and emphasizing the importance of validation in cluster identification.

Findings

Only ~35% of previously catalogued clusters are confirmed.

Many identified overdensities are likely false positives.

The actual cluster population size is close to previous estimates.

Abstract

The number of star clusters that populate the Large Magellanic Cloud (LMC) at deprojected distances < 4 deg has been recently found to be nearly double the known size of the system. Because of the unprecedented consequences of this outcome in our knowledge of the LMC cluster formation and dissolution histories, we closely revisited such a compilation of objects and found that only ~ 35 per cent of the previously known catalogued clusters has been included. The remaining entries are likely related to stellar overdensities of the LMC composite star field, because there is a remarkable enhancement of objects with assigned ages older than log(t yr-1) ~ 9.4, which contrasts with the existence of the LMC cluster age gap; the assumption of a cluster formation rate similar to that of the LMC star field does not help to conciliate so large amount of clusters either; and nearly 50 per cent of them come from cluster search procedures known to produce more than 90 per cent of false detections. The lack of further analyses to confirm the physical reality as genuine star clusters of the identified overdensities also glooms those results. We support that the actual size of the LMC main body cluster population is close to that previously known.