Introducing the FirstLight project: UV luminosity function and scaling relations of primeval galaxies

Abstract: We introduce the FirstLight project that aims to generate a large database of high-resolution, zoom-in simulations of galaxy formation around the epoch of reionisation ($z\geq6$). The first results of this program agree well with recent observational constraints at z=6-8, including the UV luminosity function and galaxy stellar mass function, as well as the scaling relationships between halo mass, stellar mass, and UV magnitude. The UV luminosity function starts to flatten below MUV>-14 due to stellar feedback in halos with maximum circular velocities of V=30-40 km/s. The power-law slope of the luminosity function evolves rapidly with redshift, reaching a value of alpha=-2.5 at z=10. On the other hand, the galaxy stellar mass function evolves slowly with time between z=8-10, in particular at the low-mass end.