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The detailed structure and the onset of galaxy formation in low-mass gaseous dark matter haloes

Benitez-Llambay, Alejandro; Frenk, Carlos

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Authors

Alejandro Benitez-Llambay



Abstract

We present a model for the formation of the first galaxies before and after the reionization of hydrogen in the early universe. In this model, galaxy formation can only take place in dark matter haloes whose mass exceeds a redshift-dependent critical value, which, before reionization, is equal (in the simplest case) to the mass at which atomic hydrogen cooling becomes effective and, after reionization, is equal to the mass above which gas cannot remain in hydrostatic equilibrium. We define the Halo Occupation Fraction (HOF) as the fraction of haloes that host a luminous galaxy as a function of halo mass. The HOF is established by the interplay between the evolution of the critical mass and the assembly history of haloes and depends on three factors: the minimum halo mass for galaxy formation before reionization, the redshift of reionization, and the intensity of the (evolving) external photoheating rate. Our fiducial model predicts a cutoff in the galaxy mass function at a present-day halo mass, M200 ∼ 3 × 108M⊙; 100% occupation at M200 > 5 × 109M⊙; and a population of starless gaseous haloes of present-day mass in the range 106 ≲ M200/M⊙ ≲ 5 × 109, in which the gas is in thermal equilibrium with the ultraviolet background radiation and in hydrostatic equilibrium in the gravitational potential of the halo. The transition between HOF = 0 and HOF = 1 reflects the stochastic nature of halo mass growth. We explore how these characteristic masses vary with model assumptions and parameter values. The results of our model are in excellent agreement with cosmological hydrodynamic simulations of galaxy formation.

Citation

Benitez-Llambay, A., & Frenk, C. (2020). The detailed structure and the onset of galaxy formation in low-mass gaseous dark matter haloes. Monthly Notices of the Royal Astronomical Society, 498(4), 4887-4900. https://doi.org/10.1093/mnras/staa2698

Journal Article Type Article
Acceptance Date Sep 2, 2020
Online Publication Date Sep 7, 2020
Publication Date 2020-11
Deposit Date Sep 8, 2020
Publicly Available Date Oct 6, 2020
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 498
Issue 4
Pages 4887-4900
DOI https://doi.org/10.1093/mnras/staa2698
Public URL https://durham-repository.worktribe.com/output/1262722

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Copyright Statement
This article has been accepted for publication in Monthly notices of the Royal Astronomical Society. ©: 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.






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