The VMC survey - XV. The Small Magellanic Cloud--Bridge connection history as traced by their star cluster populations

TL;DR

This study analyzes star cluster populations in the outer Small Magellanic Cloud to understand its interaction history with the Large Magellanic Cloud, revealing age distributions and spatial patterns indicative of past galactic interactions.

Contribution

It provides a homogeneous analysis of cluster ages and spatial distribution, highlighting the connection between the SMC's cluster populations and its interaction history with the LMC.

Findings

Older clusters are generally farther from the galaxy's center.

A trail of younger clusters follows the Wing/Bridge components.

An excess of young clusters suggests past interactions with the LMC.

Abstract

We present results based on YJKs photometry of star clusters located in the outermost, eastern region of the Small Magellanic Cloud (SMC). We analysed a total of 51 catalogued clusters whose colour--magnitude diagrams (CMDs), having been cleaned from field-star contamination, were used to assess the clusters' reality and estimate ages of the genuine systems. Based on CMD analysis, 15 catalogued clusters were found to be possible non-genuine aggregates. We investigated the properties of 80% of the catalogued clusters in this part of the SMC by enlarging our sample with previously obtained cluster ages, adopting a homogeneous scale for all. Their spatial distribution suggests that the oldest clusters, log(t yr-1) >= 9.6, are in general located at greater distances to the galaxy's centre than their younger counterparts -- 9.0 <= log(t yr-1) <= 9.4 -- while two excesses of clusters are seen at log(t yr-1) ~ 9.2 and log(t yr-1) ~ 9.7. We found a trail of younger clusters which follow the Wing/Bridge components. This long spatial sequence does not only harbour very young clusters, log(t yr-1) ~ 7.3, but it also hosts some of intermediate ages, log(t yr-1) ~ 9.1. The derived cluster and field-star formation frequencies as a function of age are different. The most surprising feature is an observed excess of clusters with ages of log(t yr-1) < 9.0, which could have been induced by interactions with the LMC.