Metallicity and UV Dependence of Massive Star Cluster Formation Triggered by Gas Collisions (229th KDESci meeting)
ABSTRACT
Recent JWST observations are beginning to reveal the sites of massive star cluster formation in the early Universe at z ~ 4–10 (e.g., Adamo et al. 2024), although the formation process of such clusters is still not well understood. In our previous studies, we showed that gas collisions associated with galaxy interactions can efficiently trigger the formation of massive star clusters (Maeda et al. 2021, 2024). In the early Universe, however, low metallicity and strong ultraviolet (UV) radiation fields may substantially alter the conditions for star formation. In this study, we extend the model of Maeda et al. (2024) to environments representative of the early Universe and investigate star cluster formation using three-dimensional ideal MHD simulations that include self-gravity, heating and cooling, chemical reactions, and stellar feedback. We find that even in low-metallicity environments, the mass of the resulting star clusters is determined primarily by the ram pressure of the collision, with only a weak dependence on metallicity and UV intensity. This behavior can be explained by the critical mass for gravitational collapse in the post-shock layer, where the magnetic field is strongly amplified. Based on these results, we construct a model for massive star cluster formation triggered by gas collisions in the early Universe and discuss its implications through comparison with observed cluster masses.
