2026/03/24 by Tae Bong Jeong, Alessandra Venditti, Volker Bromm +4
#astro-ph.GA
Observing the first generation of Population~III (Pop~III) stars is one of the most demanding challenges in astronomy. Indeed, Pop~III stars are expected to predominantly form within faint minihalos at early times with a top-heavy initial mass function, resulting in efficient metal enrichment and a fast transition to Pop~II-dominated systems. However, recent surveys with JWST have identified galaxies at the end of the Epoch of Reionization (EoR) with possible signatures of significant Pop~III star formation even at these later times. We here explore the physical conditions required to produce massive Pop~III starbursts during the EoR, using cosmological radiation-hydrodynamic zoom-in simulations. We specifically focus on galaxies with a virial (dynamical) mass of M\rm vir≈108M\odot at 7\lesssim z\lesssim8, i.e., the atomic-cooling halos that could be potential sites for such maximal Pop~III starbursts. In particular, we vary the strength of Lyman-Werner (LW) background radiation up to J\rm LW≤104J21, further imposing a high star formation efficiency (ε\rm ff=1.0). Our results show that Pop~III starbursts, observable in strongly-lensed survey fields like GLIMPSE, can occur in the presence of a sufficiently high LW flux (with \gtrsim103J21), leading to delayed, but intense Pop~III star formation. However, even for such high LW fluxes, the Pop~III starburst mass is limited to M⋆,\rm Pop~III<106M\odot, as strong internal metal enrichment occurs after the first Pop~III supernova explosions within the simulated galaxies. While the conditions favoring observable Pop~III starbursts are expected to be rare, we anticipate that future and ongoing large-volume surveys leveraging gravitational lensing will detect multiple cases of Pop~III starbursts in the EoR.