2019MNRAS.488.5551N

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 >= 6). The faint-end of the galaxy LF at these redshifts provides powerful constraints on different dark matter (DM) 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 ∼ 10^–22 eV), also known as fuzzy dark matter (FDM), and examine the predictions for the galaxy stellar mass function and LF at z >= 6 for a range of FDM masses. We find that for FDM models with bosonic mass m = 5 x 10^–22 eV, the number density of galaxies with stellar mass M_*∼₁₀7^M_☉ is suppressed by ∼40 per cent at z = 9, ∼20 per cent at z = 5, and the UV LFs within magnitude range of -16 < M_UV < -14 is suppressed by ∼60 per cent at z = 9, ∼20 per cent at z = 5 comparing to the cold dark matter counterpart simulation. Comparing our predictions with current measurements of the faint-end LFs (-18 <= M_UV <= -14), we find that FDM models with m₂₂ < 5 x 10^–22 are ruled out at 3σ confidence level. We expect that future LF measurements by James Webb Space Telescope, which will extend down to M_UV ∼ -13 for z <= 10, with a survey volume that is comparable to the Hubble Ultra Deep Field would have the capability to constrain FDM models to m >= 10^–21 eV.