Authors
Abstract
Environment plays a critical role in shaping the assembly of low-mass galaxies. Here, we use the UNIVERSEMACHINE (UM) galaxy–halo connection framework and Data Release 3 of the Satellites Around Galactic Analogs (SAGA) Survey to place dwarf galaxy star formation and quenching into a cosmological context. UM is a data-driven forward model that flexibly parameterizes galaxy star formation rates (SFRs) using only halo mass and assembly history. We add a new quenching model to UM, tailored for galaxies with m ⋆ ≲ 109 M ⊙, and constrain the model down to m ⋆ ≳ 107 M ⊙ using new SAGA observations of 101 satellite systems around Milky Way (MW)–mass hosts and a sample of isolated field galaxies in a similar mass range from the Sloan Digital Sky Survey. The new best-fit model, "UM-SAGA," reproduces the satellite stellar mass functions, average SFRs, and quenched fractions in SAGA satellites while keeping isolated dwarfs mostly star-forming. The enhanced quenching in satellites relative to isolated field galaxies leads the model to maximally rely on halo assembly to explain the observed environmental quenching. Extrapolating the model down to m ⋆ ∼ 106.5 M ⊙ yields a quenched fraction of ≳30% for isolated field galaxies and ≳80% for satellites of MW-mass hosts at this stellar mass. Spectroscopic surveys can soon test this specific prediction to reveal the relative importance of internal feedback, cessation of mass and gas accretion, satellite-specific gas processes, and reionization for the evolution of faint low-mass galaxies.Details
| Publication | The Astrophysical Journal, Volume 976, Issue 1, id.119, 29 pp. |
| Publication Date | November 2024 |
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| arXiv | arXiv:2404.14500 |
| Bibcode | 2024ApJ...976..119W |
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| E-Print Comment(s) | 35 pages, 16 figures, 2 tables. UM-SAGA best-fit model and source code: https://bitbucket.org/RW-Stanford/universemachine-saga/src/main/ This paper is part of the SAGA Survey Data Release 3: https://sagasurvey.org; The Astrophysical Journal, Volume 976, Number 1, 119, 2024; doi:10.3847/1538-4357/ad7f4c |