The luminosity function, halo masses and stellar masses of luminous Lyman-break galaxies at redshifts 5 < z < 6

Abstract

We present the results of a study of a large sample of luminous (z'{AB} L*) of the UV-selected luminosity function at high redshift. When combined with literature studies of the fainter LBG population, our new sample provides improved constraints on the luminosity function of redshift 5<z<6 LBGs over the luminosity range 0.1L*<L<10L*. A maximum likelihood analysis returns best-fitting Schechter function parameters of M*_1500=-20.73, phi*=0.0009 Mpc^-3 and alpha=-1.66 for the luminosity function at z=5, and M*_1500 = -20.04, phi*=0.0018 Mpc^-3 and alpha=-1.71 at z=6. In addition, an analysis of the angular clustering properties of our LBG sample demonstrates that luminous 5<z<6 LBGs are strongly clustered (r_0 = 8.1 Mpc), and are consistent with the occupation of dark matter halos with masses of ~10^{11.5-12.0} Msun. Moreover, by stacking the available multi-wavelength imaging data for the high-redshift LBGs it is possible to place useful constraints on their typical stellar mass. The results of this analysis suggest that luminous LBGs at 5<z<6 have an average stellar mass of ~10^10 Msun, consistent with the results of the clustering analysis assuming plausible values for the ratio of stellar to dark matter. Finally, by combining our luminosity function results with those of the stacking analysis we derive estimates of ~1x10^7 Msun Mpc^-3 and 4x10^6 Msun Mpc^-3 for the stellar mass density at z~5 and z~6 respectively.