A PHYSICAL MODEL OF Lyα EMITTERS

We present a simple physical model for populating dark matter halos with Ly alpha emitters (LAEs) and predict the properties of LAEs at z approximate to 3-7. The central tenet of this model is that the Ly alpha 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 star formation efficiency (SFE). An efficiency of 2.5% provides the best fit to the Ly alpha luminosity function (LF) at redshift z = 3.1, and we use this SFE to construct Ly alpha LFs at other redshifts. Our model reproduces the Ly alpha LFs, stellar ages, SFR approximate to 1-10 M(circle dot) yr(-1), stellar masses similar to 10(7) to 10(8) M(circle dot), and the clustering properties of LAEs at z approximate to 3-7. We find the spatial correlation lengths r(o) approximate to 3-6 h(-1) Mpc, in agreement with the observations. Finally, we estimate the field-to-field variation approximate to 30% for current volume and flux limited surveys, again consistent with observations. Our results suggest that the star formation, and hence Ly alpha emission in LAEs can be powered by accretion of new material. Relating the accreted mass, rather than the total mass, to the Ly alpha luminosity of LAEs naturally gives rise to their duty cycle.