Models for dusty Ly alpha emitters at high redshift

Models are presented for the Ly alpha emission of dusty high-redshift galax ies by combining the Press-Schechter formalism with a treatment of the inho mogeneous dust distribution inside galaxies. It is found that the amount of Ly alpha radiation escaping from the galaxies strongly depends on the time over which the dust is produced through stellar activity and on the ambien t inhomogeneity of the H II regions that surround the ionizing OB stars. Go od agreement is found with recent observations, as well as with previous no ndetections. Although a detailed determination of the individual model para meters is precluded by uncertainties, we find that (1) the dust content in primordial galaxies builds up in no more than similar to 5 x 10(8) yr, (2) the galactic H II regions are inhomogeneous with a cloud-covering factor of order unity, and (3) the overall star formation efficiency is at least sim ilar to 5%. It is predicted that future observations can detect these Ly al pha galaxies up to redshifts of similar to 8. If the universe is reionized at z(r) less than or similar to 8, the corresponding decline in the number of Ly alpha emitters at z greater than or similar to z(r) could prove to be a useful probe of the reionization epoch.