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The Lyman-α forest as a diagnostic of the nature of the dark matter

Garzilli, Antonella; Magalich, Andrii; Theuns, Tom; Frenk, Carlos S; Weniger, Christoph; Ruchayskiy, Oleg; Boyarsky, Alexey

The Lyman-α forest as a diagnostic of the nature of the dark matter Thumbnail


Antonella Garzilli

Andrii Magalich

Christoph Weniger

Oleg Ruchayskiy

Alexey Boyarsky


The observed Lyman-α flux power spectrum (FPS) is suppressed on scales below ∼ 30 km s−1. This cutoff could be due to the high temperature, T0, and pressure, p0, of the absorbing gas or, alternatively, it could reflect the free streaming of dark matter particles in the early universe. We perform a set of very high resolution cosmological hydrodynamic simulations in which we vary T0, p0 and the amplitude of the dark matter free streaming, and compare the FPS of mock spectra to the data. We show that the location of the dark matter free-streaming cutoff scales differently with redshift than the cutoff produced by thermal effects and is more pronounced at higher redshift. We, therefore, focus on a comparison to the observed FPS at z > 5. We demonstrate that the FPS cutoff can be fit assuming cold dark matter, but it can be equally well fit assuming that the dark matter consists of ∼7 keV sterile neutrinos in which case the cutoff is due primarily to the dark matter free streaming.


Garzilli, A., Magalich, A., Theuns, T., Frenk, C. S., Weniger, C., Ruchayskiy, O., & Boyarsky, A. (2019). The Lyman-α forest as a diagnostic of the nature of the dark matter. Monthly Notices of the Royal Astronomical Society, 489(3), 3456-3471.

Journal Article Type Article
Acceptance Date Jul 18, 2019
Online Publication Date Aug 8, 2019
Publication Date Nov 30, 2019
Deposit Date Aug 13, 2019
Publicly Available Date Aug 13, 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 489
Issue 3
Pages 3456-3471


Accepted Journal Article (1.8 Mb)

Copyright Statement
This article has been accepted for publication in the Monthly notices of the Royal Astronomical Society ©: 2019 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

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