The SUNBIRD Survey: Insights into small-scale star formation mechanisms through near-infrared study of Young Massive Clusters

Abstract

We draw the K-band luminosity functions (CLFs) of young massive clusters (YMCs) hosted by 34 SUNBIRD targets to evaluate the impact of the host galaxy environment on their YMC properties. The depth and high resolution of the NIR images (PSF ∼ 0.1”) allow us to test whether CLF power-law slopes (α) of high star-forming galaxies are similar to those of gas-poor low star formation rate (SFR) galaxies. We found that α ranges between 1.53 and 2.41 with a median value of 1.87 ± 0.23. We also performed correlation searches between α and the host global properties and noticed that α decreases with an increasing SFR and SFR density. On sub-galactic scales, CLF slopes of cluster-rich galaxies differ by ∼0.5. Our NIR CLF analyses suggest that the extreme environment of high SFR galaxies such as the SUNBIRD sample is likely to affect the formation mechanisms of YMCs and hence to govern the ongoing small-scale SF processes of the host galaxy.