The visibility of Lymanemitters: constraining reionization, ionizing photon escape fractions and dust

We build a physical model for high-redshift Lyman α emitters (LAEs) by coupling state-ofthe- art cosmological simulations (GADGET-2) with a dust model and a radiative transfer code (PCRASH).We post-process the cosmological simulation with PCRASH using five different values of the escape fraction of hydrogen ionizing photons (fesc = 0.05, 0.25, 0.5, 0.75, 0.95) until reionization is complete, i.e. the average neutral hydrogen fraction drops to (χHI) ≃ 10-4. Then, the only free parameter left to match model results to the observed Lyα and UV luminosity functions of LAEs at z≃6.6 is the relative escape of Lyman α (Lyα ) and continuum photons from the galactic environment (fα/fc).We find a three-dimensional degeneracy such that the theoretical model can be reconciled with observations for an intergalactic medium Lyα transmission (Tα)LAE ≃ 38-50 per cent (which translates to (χHI) ≃ 0.5-10-4 for Gaussian emission lines), fesc ≃ 0.05-0.50 and fα/fc ≃ 0.6-1.8.