Models for Dusty Lyα Emitters at High Redshift

Abstract

Models are presented for the Ly{alpha} emission of dusty high-redshift galaxies by combining the Press-Schechter formalism with a treatment of the inhomogeneous 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 ambient inhomogeneity of the H ii regions that surround the ionizing OB stars. Good agreement is found with recent observations, as well as with previous nondetections. Although a detailed determination of the individual model parameters is precluded by uncertainties, we find that (1) the dust content in primordial galaxies builds up in no more than {approximately}5{times}10{sup 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 {approximately}5{percent}. It is predicted that future observations can detect these Ly{alpha} galaxies up to redshifts of {approximately}8. If the universe is reionized at z{sub r} {approx_lt}8, the corresponding decline in the number of Ly{alpha} emitters at z{approx_gt}z{sub r} could prove to be a useful probe of the reionization epoch. {copyright} {ital {copyright} 1999.} {ital The American Astronomical Society}