The visibility of Lyman alpha emitters during reionization

We present the first Lyman alpha emitter (LAE) study that combines: (i) cosmological smoothed particle hydrodynamic (SPH) simulations run using gadget-2, (ii) radiative transfer simulations (crash) and (iii) a previously developed LAE model. This complete LAE model accounts for the intrinsic LAE, Ly alpha/continuum luminosity, dust enrichment and Ly alpha transmission through the intergalactic medium (IGM) to quantify the effects of reionization, dust and velocity fields on the Ly alpha and UV luminosity functions (LFs). We find that a model neglecting dust sorely fails to reproduce either the slope or the magnitude of the observed Ly alpha and UV LFs. Clumped dust is required to simultaneously fit the observed UV and Ly alpha LFs, such that the intrinsic Ly alpha-to-continuum luminosity is enhanced by a factor f(alpha)/f(c) similar to 1.5 (3.7) excluding (including) peculiar velocities. The higher value including velocity fields arises since LAEs reside in large potential wells and inflows decrease their Ly alpha transmission. For the first time, a degeneracy is found between the ionization state of the IGM and the clumping of dust inside high-redshift galaxies. The Ly alpha LF z similar to 5.7 can be well reproduced (to within a 5 Sigma error) by a wide range of IGM average neutral hydrogen fraction, 3.4 x 10-3 < <> < 0.16, provided that the increase in the Ly alpha transmission through a more ionized IGM is compensated by a decrease in the Ly alpha escape fraction from the galaxy due to dust absorption. The physical properties of LAEs are presented along with a discussion of the assumptions adopted.