Year: 2026
Type: article
Abstract: It is widely believed that the ultraviolet background produced during the epoch of reionization conspires against the formation of low-mass galaxies. Indeed, this mechanism is often invoked as part of the solution to the so-called “missing satellites problem.” In this paper we employ FIREbox , a large-volume cosmological simulation based on the Feedback In Realistic Environments physics model, to characterize the mechanisms governing galaxy ignition in the postreionization era. By carefully matching recently ignited halos (with stellar ages below 100 Myr at the time of selection) to halos that failed to form any stars, we conclude that the presence of cold dense gas and halo concentration helps incite the process of galaxy formation. Concretely, we find that 100% of recently ignited halos experience cold dense gas enhancements relative to their matched failed counterparts. Likewise, approximately 83% display enhancements in both cold dense gas and Navarro–Frenk–White concentration ( c NFW ), while the remaining ∼17% exhibit enhanced cold dense gas content and suppressed c NFW values. Lastly, our simulation suggests that galaxy ignition can occur as late as z = 2, potentially allowing us to observationally catch this process “in the act” in the foreseeable future.
Source: The Astrophysical Journal
Institutions: Pomona College, Carnegie Observatories, California State Polytechnic University, California Institute of Technology, California State University, San Bernardino, The University of Texas at Austin, Yale University, University of Zurich, University of California, Davis, University of Southern California
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $4,499
Awards: The baryonic cycle in galaxies from Cosmic Dawn to Cosmic Noon, G103270039, G1338664626, G256731684, Driving Community Learning at Cosmic Scales: Defining Ultrafaint Dwarf Galaxies & Radical Mentorship Methods, G3249264430, Collaborative Research: Magellanic dwarfs as a key laboratory for dwarf galaxy formation, CAREER: Galactic Archeology: Understanding the Building Blocks of the Milky Way across Cosmic Time, G498445101, G5036242617, G5348194189, Collaborative Research: Starless Dark Matter Halos as a Definitive Test of Dark Matter Models, G5568641063, G6259134207, Collaborative Research: Constraining Fuzzy Dark Matter with Cosmological Simulations, G6870546155, G7064235636, Postdoctoral Fellowship: MPS-Ascend: Probing small galactic scales in large volumes with the Rubin Observatory, G8201268980, Collaborative Research: NSF BSF: Disk Formation over Cosmic Time, G993971353
OpenAlex ID: W7125393655