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Fluorescent rings in star-free dark matter haloes

Sykes, Calvin; Fumagalli, Michele; Cooke, Ryan; Theuns, Tom; Benítez–Llambay, Alejandro

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Alejandro Benítez–Llambay


Photoheating of the gas in low-mass dark matter (DM) haloes prevents baryons from cooling, leaving the haloes free of stars. Gas in these ‘dark’ haloes remains exposed to the ultraviolet background (UVB), and so is expected to emit via fluorescent recombination lines. We present a set of radiative transfer simulations, which model dark haloes as spherical gas clouds in hydrostatic equilibrium with a DM halo potential, and in thermal equilibrium with the UVB at redshift z = 0. We use these simulations to predict surface brightnesses in Hα, which we show to have a characteristic ring-shaped morphology for haloes in a narrow mass range between ≃ 109.5 and 109.6 M⊙. We explore how this emission depends on physical parameters such as the DM density profile and the UVB spectrum. We predict the abundance of fluorescent haloes on the sky, and discuss possible strategies for their detection. We demonstrate how detailed observations of fluorescent rings can be used to infer the properties of the haloes which host them, such as their density profiles and the mass-concentration relation, as well as to directly measure the UVB amplitude.


Sykes, C., Fumagalli, M., Cooke, R., Theuns, T., & Benítez–Llambay, A. (2019). Fluorescent rings in star-free dark matter haloes. Monthly Notices of the Royal Astronomical Society, 487(1), 609-621.

Journal Article Type Article
Acceptance Date Apr 22, 2019
Online Publication Date May 4, 2019
Publication Date Jul 31, 2019
Deposit Date May 7, 2019
Publicly Available Date May 7, 2019
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 487
Issue 1
Pages 609-621


Accepted Journal Article (855 Kb)

Copyright Statement
© 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society.

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