High-redshift Ly alpha emitters:clues on the Milky Way infancy

With the aim of determining if Milky Way (MW) progenitors could be identified as high-redshift Lyman Alpha Emitters (LAEs), we have derived the intrinsic properties of z approximate to 5.7 MW progenitors, which are then used to compute their observed Ly alpha luminosity, L(alpha), and equivalent width (EW). MW progenitors visible as LAEs are selected according to the canonical observational criterion, L(alpha) > 10(42) erg s(-1) and EW > 20 angstrom. Progenitors of MW-like galaxies have L(alpha) = 10(39-43.25) erg s(-1), making some of them visible as LAEs. In any single MW merger tree realization, typically only one (out of approximate to 50) progenitor meets the LAE selection criterion, but the probability of having at least one LAE is very high, P = 68 per cent. The identified LAE stars have ages t(*) approximate to 150-400 Myr at z approximate to 5.7, with the exception of five small progenitors with t(*) <5 Myr and large EW = 60-130 angstrom. LAE MW progenitors provide > 10 per cent of the halo very metal-poor stars [Fe/H] <-2, thus establishing a potentially fruitful link between high-z galaxies and the local Universe.