New galaxy UV luminosity constraints on warm dark matter from JWST

Abstract: We exploit the recent {\it James Webb Space Telescope} (JWST) determination of galaxy UV luminosity functions over the redshift range $z=9-14.5$ to derive constraints on warm dark matter (WDM) models. The delayed structure formation in WDM universes make high-redshift observations a powerful probe to set limits on the particle mass $m_\mathrm{x}$ of WDM candidates. By integrating these observations with blank-field surveys conducted by the {\it Hubble Space Telescope} (HST) at redshifts $z=4-8$, we impose constraints on both astrophysical parameters ($\beta$, $\gamma$, $\epsilon_{\mathrm N}$, $M_c$ for a double-power law star formation efficiency, and $\sigma_{M_{\mathrm{UV}}}$ for a Gaussian magnitude-halo mass relation) and the WDM parameter (dark matter particle mass $m_\mathrm{x}$) simultaneously. We find a new limit of $m_\mathrm{x} \geq 3.2$ keV for the mass of thermal relic WDM particles at $95\%$ confidence level. This bound is tighter than the most stringent result derived using HST data before. Future JWST observations could further reduce the observation uncertainties and improve this constraint.