Predictions for the Abundance of High-redshift Galaxies in a Fuzzy Dark Matter Universe

During the last decades, rapid progress has been made in measurements of the rest-frame ultraviolet (UV) luminosity function (LF) for high-redshift galaxies ($z\ge 6$). The faint-end of the galaxy LF at these redshifts provides powerful constraints on different dark matter models that suppress small-scale structure formation. In this work we perform full hydrodynamical cosmological simulations of galaxy formation using an alternative DM model composed of extremely light bosonic particles ($m\sim {10}^{-22}$ eV), also known as fuzzy dark matter (FDM), and examine the predictions for the galaxy stellar mass function and luminosity function at $z\ge 6$ for a range of FDM masses. We find that for FDM models with bosonic mass $m=5\times {10}^{-22}$ eV, the number density of galaxies with stellar mass ${\mathrm{M}}_{\ast }\sim {10}^7{\mathrm{M}}_{\odot }$ is suppressed by $\sim 40\mathrm{\%}$ at z = 9, $\sim 20\mathrm{\%}$ at z = 5, and the UV LFs within magnitude range of -16 < $M_{\mathrm{U}\mathrm{V}}$ < -14 is suppressed by $\sim 60\mathrm{\%}$ at $z = 9$,$\sim 20%$at$z = 5$ comparing to the CDM counterpart simulation. Comparing our predictions with current measurements of the faint-end LFs ($-18 \leqslant M_{\rm UV} \leqslant -14$),wefindthatFDMmodelswith$m_{22} < 5\times10^{-22}$areruledoutat$3\sigma$ confidence level. We expect that future LF measurements by James Webb Space Telescope (JWST), which will extend down to $M_{\mathrm{U}\mathrm{V}}\sim -13$ for $z\lesssim 10$, with a survey volume that is comparable to the Hubble Ultra Deep Field (HUDF) would have the capability to constrain FDM models to $m\gtrsim {10}^{-21}$ eV.