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Arxiv: High-redshift, small-scale tests of ultralight axion dark matter using Hubble and Webb galaxy UV luminosities Published: 4/17/2024 8:01:42 AM Updated: 4/17/2024 8:01:42 AM

Paper abstract: We calculate the abundance of UV-bright galaxies in the presence ofultralight axion dark matter (DM), finding that axions suppress their formationbut with a non-trivial dependence on redshift and luminosity. We thus set thefirst limits on axion DM using a combination of Planck cosmic microwavebackground (CMB) and UV luminosity function (UVLF) data. We exclude a singleaxion as all the DM for m_{ax} < 10^{-21.6} eV and limit axions with -26 10) galaxies from the James Webb SpaceTelescope (JWST). We find that these data are consistent with the HST UVLFassuming LambdaCDM and our flexible parametric model of UV luminosity.Combining HST and JWST UVLF data does not improve our constraints beyond HSTalone, but future JWST measurements have the potential to improve these resultssignificantly. We also find an excess of low-mass halos (< 10^9 M_\odot) at z <3, which could be probed by sub-galactic structure probes (e.g., stellarstreams, satellite galaxies and strong lensing).