The number density of small dark matter (DM) haloes hosting faint high-redshift galaxies is sensitive to the DM free-streaming properties. However, constraining these DM properties is complicated by degeneracies with the uncertain baryonic physics governing star formation. In this work, we use a flexible astrophysical model and a Bayesian inference framework to analyse ultraviolet (UV) luminosity functions (LFs) at z = 6-8. We vary the complexity of the astrophysical galaxy model (single versus double power law for the stellar-halo mass relation) as well as the matter power spectrum [cold DM versus thermal relic warm DM (WDM)], comparing their Bayesian evidences. Adopting a conservatively wide prior range for the WDM particle mass, we show that the UV LFs at z = 6-8 only weakly favour cold DM over WDM. We find that particle masses of ≤ 2 keV are rejected at a 95 per cent credible level in all models that have a WDM-like power spectrum cutoff. This bound should increase to ∼2.5 keV with the James Webb Space Telescope (JWST).

Constraints on warm dark matter from UV luminosity functions of high-z galaxies with Bayesian model comparison

Rudakovskyi A.;Mesinger A.;Gillet N.
2021

Abstract

The number density of small dark matter (DM) haloes hosting faint high-redshift galaxies is sensitive to the DM free-streaming properties. However, constraining these DM properties is complicated by degeneracies with the uncertain baryonic physics governing star formation. In this work, we use a flexible astrophysical model and a Bayesian inference framework to analyse ultraviolet (UV) luminosity functions (LFs) at z = 6-8. We vary the complexity of the astrophysical galaxy model (single versus double power law for the stellar-halo mass relation) as well as the matter power spectrum [cold DM versus thermal relic warm DM (WDM)], comparing their Bayesian evidences. Adopting a conservatively wide prior range for the WDM particle mass, we show that the UV LFs at z = 6-8 only weakly favour cold DM over WDM. We find that particle masses of ≤ 2 keV are rejected at a 95 per cent credible level in all models that have a WDM-like power spectrum cutoff. This bound should increase to ∼2.5 keV with the James Webb Space Telescope (JWST).
2021
Settore FIS/05 - Astronomia e Astrofisica
dark matter; galaxies: luminosity function; reionization
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/110439
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