Newborn super star clusters at Cosmic Noon seen through gravitational lensing
Super star clusters with masses > 1e6 Msun are thought to be progenitors of globular clusters (GCs). Their births however are seldomly seen in the local Universe. Given radiation and kinetic feedbacks that regulate star formation, contribution to cosmic reionization through efficient Lyman continuum (LyC) escape, and the puzzle of chemically peculiar populations found in most globular clusters, much is to be understood about what happens in the immediate environment of these young systems that host a large number of massive stars. I will present a photometric and spectroscopic study of a highly magnified, LyC-leaking super star cluster with a mass ~1e7 Msun and an age ~3–4 Myr, in a lensed Cosmic Noon galaxy. We found dense photoionized clouds at just ~ 10 pc that are highly enriched with nitrogen. We theorize that these dense clouds originate from massive star ejecta and may have implications for the origin of chemically peculiar stars. I will also discuss another lensed star cluster in the same galaxy that has a lensing anomaly and show intense Fe III fluorescent emissions pumped by Lyman alpha radiation. I discuss a theory of trapped Lyman alpha radiation to explain this unusual spectral phenomenon, which again hints at an extremely gas-enshrouded environment caused by massive star ejecta inside a compact young super star cluster. These findings call for a better understanding of the interplay between radiation, gravity, gas and massive star evolution in young super star clusters.