Spatiotemporal map of star clusters in the Magellanic Clouds using Gaia: synchronized peaks and radial shrinkage of cluster formation

Abstract

We present a detailed view of cluster formation (CF) to trace the evolution and interaction history of the Magellanic Clouds (MCs) in the last 3.5 Gyr. Using the Gaia DR3 data, we parametrized 1710 and 280 star clusters in the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC), where 847 and 113 clusters are newly characterized in the outer LMC and SMC, respectively. We estimated the age–extinction–metallicity–distance parameters using an automated fitting of the colour– magnitude diagram (CMD) after field star removal, followed by a Markov chain Monte Carlo technique. We report a first-time detection of two synchronized CF peaks in the MCs at 1.5 ± 0.12 Gyr and 800 ± 60 Myr. We recommend that the choice of the metallicity (Z) values of isochrones for clusters with age ≤ 1–2 Gyr are ZLMC = 0.004–0.008 and ZSMC = 0.0016–0.004 for the LMC and SMC, respectively. We found evidence for spiral arms in the LMC, as traced by the cluster count profiles over the last 3.5 Gyr. The density maps provide evidence of ram-pressure stripping in the north-east of the LMC, a severe truncation of CF in the south of the LMC, and a radial shrinkage of CF in the SMC in the last 450 Myr. The last SMC–LMC interaction (∼150 Myr) resulted in a substantial CF in the north and eastern SMC, with a marginal impact on the LMC. This study provides important insights into the CF episodes in the MCs and their connection to the LMC–SMC–MW interactions.