The visibility of Lyman α emitters: constraining reionization, ionizing photon escape fractions and dust

We build a physical model for high-redshift Lyman alpha emitters (LAEs) by coupling state-of-the-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 (f(esc) = 0.05, 0.25, 0.5, 0.75, 0.95) until reionization is complete, i.e. the average neutral hydrogen fraction drops to aEuro chi(H i)aEuro parts per thousand a parts per thousand integral 10(-4). Then, the only free parameter left to match model results to the observed Ly alpha and UV luminosity functions of LAEs at z a parts per thousand integral 6.6 is the relative escape of Lyman alpha (Ly alpha ) and continuum photons from the galactic environment (f(alpha)/f(c)). We find a three-dimensional degeneracy such that the theoretical model can be reconciled with observations for an intergalactic medium Ly alpha transmission aEuroT(alpha)aEuro parts per thousand(LAE) a parts per thousand integral 38-50 per cent (which translates to aEuro chi(H i)aEuro parts per thousand a parts per thousand integral 0.5-10(-4) for Gaussian emission lines), f(esc) a parts per thousand integral 0.05-0.50 and f(alpha)/f(c) a parts per thousand integral 0.6-1.8.