Efficient Star Formation in Massive Galaxies at Cosmic Dawn
Zachary Andalman, Princeton University
Over the past two years, the James Webb Space Telescope (JWST) has detected tens of galaxies at cosmic dawn, an epoch starting with the formation of the first stars ~100Myr after the big bang and ending with the reionization of the intergalactic medium ~1Gyr after the big bang. The stellar masses and star formation rates inferred from these galaxies imply an early period of rapid star formation, in conflict with theoretical predictions. We use the cosmological hydrodynamics code RAMSES to run high-resolution (Δ~10pc) simulations of star formation in massive galaxies at cosmic dawn, accounting for density fluctuations on unresolved scales. In the present day, star formation is regulated by massive stars (>8M⊙), which inject energy into the surrounding medium through photoionizing radiation and supernovae explosions. In our simulated galaxies at cosmic dawn, these feedback processes are suppressed due to the dense, turbulent, and low metallicity conditions of the early Universe, resulting in a star formation efficiency (SFE) ~10%, consistent with observations. However, the precise SFE is sensitive to the local gas conditions. More robust predictions will require simulations which treat radiation self-consistently and resolve scales ~1pc.