WERE PROGENITORS OF LOCAL L* GALAXIES Lyα EMITTERS AT HIGH REDSHIFT?

The Lyα emission has been observed from galaxies over a redshift span z ∼ 0-8.6. However, the evolution of high-redshift Lyα emitters (LAEs), and the link between these populations and local galaxies, remains poorly understood. Here, we investigate the Lyα properties of progenitors of a local L* galaxy by combining cosmological hydrodynamic simulations with three-dimensional radiative transfer calculations using the new ART2 code. We find that the main progenitor (the most massive one) of a Milky-Way-like galaxy has a number of Lyα properties close to those of observed LAEs at z ∼ 2-6, but most of the fainter ones appear to fall below the detection limits of current surveys. The Lyα photon escape fraction depends sensitively on a number of physical properties of the galaxy, such as mass, star formation rate, and metallicity, as well as galaxy morphology and orientation. Moreover, we find that high-redshift LAEs show blueshifted Lyα line profiles characteristic of gas inflow, and that the Lyα emission by excitation cooling increases with redshift, and becomes dominant at z ∼> 6. Our results suggest that some observed LAEs at z ∼ 2-6 with luminosity of LLyα ∼ 1042-1043 erg s–1 may be similar to the main progenitor of the Milky Way at high redshift, and that they may evolve into present-day L* galaxies.