Detecting Lyman alpha emitters in the submillimetre

Using the results from a previously developed Lyman α/continuum production/transmission and dust enrichment model for Lyman alpha emitters (LAEs), based on cosmological smoothed particle hydrodynamics simulations, we assess the detectability of their dust-reprocessed submillimetre (submm) radiation. As supernovae (rather than evolved stars) control dust formation and destruction processes, LAEs are relatively dust-poor with respect to local galaxies: they have low dust- to-gas ratios (0.05 times the dust-to-gas ratio of the Milky Way) in spite of their relatively high metallicity, Z ~ 0.1-0.5Z_solar. Using the derived escape fraction of ultraviolet (UV) continuum photons, we compute the UV luminosity absorbed by dust and re-emitted in the far-infrared. The LAE submm fluxes correlate with their Lyman α luminosity: about (3, 1 per cent) at z = (5.7, 6.6) of the LAEs in our simulated sample (those with logL_α > 43.1) would have fluxes at 850 μm (the optimal band for detection) in excess of 0.12 mJy and will be therefore detectable at 5σ with ALMA with an integration time of only 1 h. Such detections would open a new window on the physical conditions prevailing in these most distant galaxies.