Oral Presentation

Formation of massive star cluster under radiative and stellar wind feedback: origins of extremely high N/O ratios and multiple stellar populations

Author(s): Hajime Fukushima, Hidenobu Yajima (University of Tsukuba)

Presenter: Hajime Fukushima (University of Tsukuba)

By performing 3D radiation hydrodynamics simulations with radiative and stellar wind feedback, we study the formation of young massive star clusters (YMCs). We include the metal yield by stellar wind and supernovae. We find that the young massive star clusters are only born in the high-surface density clouds where radiative feedback becomes ineffective due to strong gravitational force from the star clusters. In such a case, metal-enriched and high-density gas is formed around the star clusters. Before the supernovae occur, the high N/O ratios of gas are achieved due to stellar wind from Wolf-Rayet stars. The N/O ratios are comparable to that of discovered high-z galaxies (e.g., GN-z11). On the other hand, the oxygen-enriched gas appears after a supernova occurs inside the star cluster. Also, the N/O ratios of enriched stars are similar to those of second-population stars in globular clusters (GCs). Combining the condition of the YMC formation and the timescales of stellar evolution, we show that metal-enriched stars are only born in star clusters more massive than 1.e6 Msun. This condition of stellar multiple populations in YMCs allows us to constrain the formation site of GCs.