SIMBAD references

We present a novel method to investigate c reionization, using joint spectral information on high-redshift Lyman α emitters (LAEs) and quasi-stellar objects (QSOs). Although LAEs have been proposed as reionization probes, their use is hampered by the fact their Lyα line is damped not only by intergalactic H I but also internally by dust. Our method allows us to overcome such degeneracy. First, we carefully calibrate a reionization simulation with QSO absorption line experiments. Then we identify LAEs ({img} and equivalent width >20 Å) in two simulation boxes at z= 5.7 and 6.6 and we build synthetic images/spectra of a prototypical LAE. The surface brightness maps show the presence of a scattering halo extending up to 150 kpc from the galaxye. For each LAE we then select a small box of (10 h^–1 Mpc)³ around it and derive the optical depth τ along three viewing axes. At redshift 5.7, we find that the Lyα transmissivity {img}, almost independent of the halo mass. This constancy arises from the conspiracy of two effects: (i) the intrinsic Lyα line width and (ii) the infall peculiar velocity. At higher redshift, z= 6.6, where {img} the transmissivity is instead largely set by the local H I abundance and {img} consequently increases with halo mass, M_h, from 0.15 to 0.3. Although outflows are present, they are efficiently pressure confined by infall in a small region around the LAE; hence they only marginally affect transmissivity. Finally, we cast line of sight originating from background QSOs passing through foreground LAEs at different impact parameters, and compute the quasar transmissivity ({img}). At small impact parameters, d < 1 cMpc, a positive correlation between {img} and M_h is found at z= 5.7, which tends to become less pronounced (i.e. flatter) at larger distances. Quantitatively, a roughly 10{x} increase (from 5 {x} 10^–3 to 6 {x} 10^–2) of {img} is observed in the range log M_h= (10.4-11.6). This correlation becomes even stronger at z= 6.6. By cross-correlating {img} and {img}, we can obtain a H I density estimate unaffected by dust. At z= 5.7, the cross-correlation is relatively weak, whereas at z= 6.6 we find a clear positive correlation. We conclude by briefly discussing the perspectives for the application of the method to existing and forthcoming data.