A Physical Model of Lyman Alpha Emitters

We present a simple physical model for populating dark matter (DM) halos with Lyman Alpha Emiiters (LAEs) and predict the physical properties of LAEs at z ≈ 3− 7. The central tenet of this model is that the Lyα luminosity is proportional to the star formation rate (SFR) which is directly related to the halo mass accretion rate. The only free parameter in our model is then the starformation efficiency (SFE). An efficiency of 2.5% provides the best-fit to the Lyα luminosity function (LF) at redshift z = 3.1, and we use this SFE to construct Lyα LFs at other redshifts. Our model reproduce the Lyα LFs, stellar ages, SFR≈ 1− 10 M⊙ yr, stellar masses ∼ 10 − 10 M⊙ and the clustering properties of LAEs at z ≈ 3−7. We find the spatial correlation lengths ro ≈ 3−6 h Mpc, in agreement with the observations. Finally, we estimate the field-to-field variation ≈ 30% for current volume and flux limited surveys, again consistent with observations. Our results suggest that the star formation, and hence Lyα emission in LAEs is powered by the accretion of new material, and that the physical properties of LAEs do not evolve significantly over a wide range of redshifts. Relating the accreted mass, rather than the total mass, to the Lyα luminosity of LAEs naturally gives rise to the duty cycle of LAEs. Subject headings: galaxies: high-redshift — galaxies: Lyman alpha emitters — galaxy: luminosity function — galaxy: clustering — galaxy: correlation length