Reionization on ice

The case for substantial far infrared ice emission in local ultra-luminous infrared galaxies, expected based on the presence of mid-infrared ice absorption in their spectra and the known far-infrared optical properties of ice, is still largely unsupported by direct observation owing to insufficient far-infrared spectral coverage. Some marginal supportive evidence is presented here. A clear consequence of far-infrared ice emission is the need to extend the range of redshifts considered for submillimeter sources. This is demonstrated via the example of HDF 850.1. The solid phase of the ISM during reionization may be dominated by ice, and this could lead to the presence of reionization sources in submillimeter source catalogs. Submillimeter sources not detected at 24 mu m in the GOODS-N field are examined. Two candidate reionization sources are identified at 3.6 gm through possible Gunn-Peterson saturation in the Z band.