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The cosmic UV background and the beginning and end of star formation in simulated field dwarf galaxies

Pereira-Wilson, Matthew; Navarro, Julio F; Benítez-Llambay, Alejandro; Santos-Santos, Isabel

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Authors

Matthew Pereira-Wilson

Julio F Navarro

Alejandro Benítez-Llambay



Abstract

We use the APOSTLE cosmological simulations to examine the role of the cosmic UV background in regulating star formation (SF) in low-mass Lambda cold dark matter (ΛCDM) haloes. In agreement with earlier work, we find that after reionization SF proceeds mainly in haloes whose mass exceeds a redshift-dependent ‘critical’ mass, Mcrit, set by the structure of the haloes and by the thermal pressure of UV-heated gas. Mcrit increases from
at z ∼ 10 to
at z = 0, roughly following the average mass growth of haloes in that mass range. This implies that haloes well above or below critical at present have remained so since early times. Haloes of luminous dwarfs today were already above-critical and star forming at high redshift, explaining naturally the ubiquitous presence of ancient stellar populations in dwarfs, regardless of luminosity. The SF history of systems close to the critical boundary is more complex. SF may cease or reignite in dwarfs whose host halo falls below or climbs above the critical boundary, suggesting an attractive explanation for the episodic nature of SF in some dwarfs. Also, some subcritical haloes today may have been above critical in the past; these systems should at present make up a sizable population of faint field dwarfs lacking ongoing star formation. Although few such galaxies are currently known, the discovery of this population would provide strong support for our results. Our work indicates that, rather than stellar feedback, it is the ionizing UV background and mass accretion history what regulates SF in the faintest dwarfs.

Citation

Pereira-Wilson, M., Navarro, J. F., Benítez-Llambay, A., & Santos-Santos, I. (2022). The cosmic UV background and the beginning and end of star formation in simulated field dwarf galaxies. Monthly Notices of the Royal Astronomical Society, 519(1), 1425-1436. https://doi.org/10.1093/mnras/stac3633

Journal Article Type Article
Acceptance Date Dec 6, 2022
Online Publication Date Dec 13, 2022
Publication Date Dec 16, 2022
Deposit Date Jan 24, 2024
Publicly Available Date Jan 24, 2024
Journal Monthly Notices of the Royal Astronomical Society
Print ISSN 0035-8711
Electronic ISSN 1365-2966
Publisher Royal Astronomical Society
Peer Reviewed Peer Reviewed
Volume 519
Issue 1
Pages 1425-1436
DOI https://doi.org/10.1093/mnras/stac3633
Keywords Space and Planetary Science; Astronomy and Astrophysics
Public URL https://durham-repository.worktribe.com/output/2163138

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Copyright Statement
© 2022 The Author(s)
Published by Oxford University Press on behalf of Royal Astronomical Societ





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