Properties of host haloes of Lyman-break galaxies and Lyman α emitters from their number densities and angular clustering

We explore empirical relations between three different populations of high-redshift galaxies and their hosting dark haloes employing the halo model approach. Specifically we consider Lyman-break galaxies (LBGs) at zsimilar to 4 and at zsimilar to 5, and Lyman alpha emitters (LAEs) at zsimilar or equal to 4.86, all from the Subaru Deep Field survey extending over an area of about 600 arcmin(2). We adopt a halo occupation function (HOF) prescription to parametrize the properties of their hosting haloes and the efficiency of halo-dependent star formation. We find that the two LBG samples are well described by the halo model with an appropriate HOF. Comparing the model predictions with the observed number densities and the angular correlation functions for those galaxies, we obtain constraints on properties of their hosting haloes. A typical mass of hosting haloes for LBGs is 5 x 10(11)h(-1) M-circle dot and the expected number of LBGs per halo is similar to0.5; therefore there is an approximate one-to-one correspondence between haloes and LBGs. We also find an indication that the minimum mass of LBG hosting haloes decreases with time, although its statistical significance is not strong. We discuss the implications of these findings on the star formation history of LBGs. On the other hand, for LAEs, our simple HOF prescription fails to reproduce simultaneously the observed angular correlation function and the number density. In particular, a very high amplitude of the correlation function on scales larger than 120 arcsec cannot be easily reconciled by the HOF model; a set of parameters that account for this high correlation amplitude on large scales predict either excessive clustering on small scales or a much smaller number density than observed. While this difficulty might imply either that the distribution of LAEs within hosting haloes differs from that of dark matter, or that the strong large-scale correlation is due to the existence of an unusual, large overdense region, and so the survey region is not a representative of the zsimilar to 5 Universe, the definite answer should wait for a much wider survey of LAEs at high redshifts.