Abundance matching for low-mass galaxies in the CDM and FDM models

Abundance matching between galaxies and haloes has proven to be an informative technique, less dependent on detailed physical approximations than some other methods. We extend the discussion to the dwarf galaxies realm and to the study of the alternative hypothesis that the dark matter is composed of ultra-light particles: fuzzy dark matter. We find that, given current observations, both cold dark matter (CDM) and fuzzy dark matter (FDM) have difficulties with dwarf systems in the local group, but that, if mechanisms are proposed to alleviate these difficulties, they make radically different predictions for FDM and CDM at high redshift. These differences should allow clear observational tests with currently planned experiments, with the number of galaxies per unit volume with stellar mass over 106 M⊙ lower in FDM by factors of 10−2.7, 10−2.0, 10−1.7, 10−0.7, 10−0.1 at z = 10, 8, 6, 4, 2.