Young massive clusters in the interacting LIRG Arp 299: evidence for the dependence of star cluster formation and evolution on environment

Abstract

Archival WFC3/UVIS imaging of Arp 299 (NGC 3690E + NGC 3690W) is retrieved to investigate the young massive cluster (YMC) population of this ongoing merger. We extract 2182 cluster candidates, including 1323 high confidence photometric sources. Multiband photometry is matched with Yggdrasil models to estimate the age, mass, and extinction of each cluster. A Schechter fit of the truncated cluster mass function results in a characteristic mass ${\rm M_{*} = 1.6 \times 10^6 M_{\odot}}$. Our results confirm that intensely star-forming galaxies such as Arp 299 host more massive clusters than quiescent dwarf and normal spirals. In the case of NGC 3690E, we find that the cluster masses decrease with an increasing galactocentric radius likely due to the gas density distribution. On the other hand, the fitted age distributions of a mass-limited sample suggest that YMCs of the western component undergo stronger disruption than those hosted by the eastern galaxy. This is in agreement with the properties of the underlying cluster luminosity functions: a clear truncation at high luminosities with slopes generally shallower by $\sim 0.3$ dex than the ones of the NGC 3690E. Finally, the derived cluster formation efficiency, $\Gamma \sim 19$ percent, indicates that Arp 299 has $\sim 3-5$ times more star formation happening in bound clusters compared to the cases of gas-poor spirals like NGC 2997 and NGC 4395. The merger generally follows the $\Gamma - $ star formation rate density relation from the literature. The YMC photometric study of Arp 299 thus reveals that both formation and disruption mechanisms of the star cluster population are most likely environment-dependent.