Year: 2026
Type: preprint
Abstract: Low-mass galaxies during the Epoch of Reionization are expected to form stars in short bursts separated by periods of inactivity, but what regulates this cycle, and how sensitive it is to the modelling of stellar feedback, remains unclear. We use the MEGATRON high-redshift zoom simulation suite, in which four star-formation and stellar-feedback prescriptions are evolved from identical initial conditions, to study the regulation of stellar mass growth in galaxies with $M_{*} \sim 10^{4} - 10^{8} M_{\odot}$ at $z = 8.5$. We classify galaxies as Star-Forming, Mini-Quenched (no significant star formation over the last 10 Myr), or Quenched (no significant star formation over the last 100 Myr). The feedback prescription controls both how often galaxies are quiescent and how this depends on mass. Models with stronger or more clustered feedback yield larger quiescent fractions compared to the fiducial and Varying IMF models. Duty cycles at fixed mass also differ by factors of several between models. The cold gas profiles of Quenched galaxies are consistent with two physically distinct modes of quenching: mechanical gas evacuation, producing compact, cold gas-poor systems, and thermodynamic suppression, retaining a cold but star-formation-inactive reservoir. At these masses, quiescent galaxies fall below un-lensed JWST/NIRCam detection limits, whereas star-forming galaxies of the same mass do not, and consequently flux-limited samples will be biased towards active phases. Measuring the quiescent fraction as a function of stellar mass in lensing fields would provide a direct test of stellar-feedback models at Cosmic Dawn.
Source: arXiv (Cornell University)
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: G1468651527, G1592084823, DiRAC-2.5 - the pathway to DiRAC Phase 3, G2309215924, G2368581224, G2843074508, The DiRAC 2.5x Facility, G4251892262, G4862659593, G581313191, The Data Intensive Science Centre Network - DISCnet, DiRAC-2.5 DC - Operations 2017-2020, G6860730371, Cambridge Service for Data Driven Discovery (CSD3) - A National Data Intensive Science Cloud for Converged Simulation, AI & Analytics, G7028966183, DiRAC2: 100 Tflop/s HPC cluster procurement, DiRAC: Memory Intensive 2.5y, G8962111125, DiRAC 2.5 Operations 2017-2020, DiRAC: Memory Intensive 2.5x
OpenAlex ID: W7214990533