The YMCA (Yes, Magellanic Clouds Again) survey: probing the outer regions of the Magellanic system with VST

TL;DR

The YMCA survey used deep VST photometry to explore the outer regions of the Magellanic Clouds, revealing their stellar populations, star cluster ages, and evidence of past interactions between the Clouds.

Contribution

This study provides new deep optical data of the Magellanic Clouds' outskirts, discovering candidate star clusters and analyzing their age distribution to understand their interaction history.

Findings

Outskirts dominated by intermediate-age and old stars.

Star cluster ages suggest a close LMC-SMC fly-by 2.5-3 Gyr ago.

Discovery of candidate clusters within the age-gap period.

Abstract

The Magellanic Clouds (MCs) are the Milky Way's most massive dwarf satellites. As they also represent the closest pair of galaxies in an ongoing tidal interaction, while simultaneously infalling into the Milky Way halo, they provide a unique opportunity to study in detail an ongoing three-body encounter. We present the ``YMCA (Yes, Magellanic Clouds Again) survey: probing the outer regions of the Magellanic system with VST'' based on deep optical photometry carried out with the VLT Survey Telescope (VST). YMCA targeted 110 square degrees, in the g and i filters, in the periphery of both the MCs, including a long strip in between the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). The photometry of YMCA is sufficiently deep (50\% complete down to $g \simeq 23.5-24.0$~mag) to allow for a detailed analysis of main-sequence stars in regions of the MCs remained relatively unexplored at these faint magnitudes. The resulting colour-magnitude diagrams reveal that the outskirts of the MCs are predominantly characterized by intermediate-age and old stellar populations, with limited or negligible evidence of recent star formation. The analysis of the age distribution of star clusters (SCs) within the surveyed area, both already known and newly discovered candidates, hints at a close fly-by between the LMC and SMC that occurred $\simeq 2.5-3.0$~Gyr ago, in agreement with previous results. We also report the discovery of candidate SCs with ages within the so-called ``age-gap'', questioning its real existence.