A Physical Model of Lyα Emitters

• We present a simple physical model for populating dark matter halos with Lyα emitters (LAEs) and predict the 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 star formation 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 reproduces the Lyα LFs, stellar ages, SFR ≈1-10 M sun yr-1, stellar masses ~107to108 M sun, and the clustering properties of LAEs at z ≈ 3-7. We find the spatial correlation lengths ro ≈ 3-6 h -1 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 can be powered by accretion of new material. Relating the accreted mass, rather than the total mass, to the Lyα luminosity of LAEs naturally gives rise to their duty cycle.

Nyckelord

accretion

accretion disks

dark matter

galaxies: evolution

galaxies: halos

galaxies: high-redshift

galaxies: luminosity function

mass function

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