Potential Measurement of the Luminosity Function of 158 Micron [c Ii] at High Redshifts: a Test of Galaxy Formation Models

Galaxy formation scenarios predict a burst of star formation in normal galaxies at a redshift between zD 2 and zD 6 (e.g., Katz & Gunn 1991) ; such a starburst may be accompanied by a signiÐcant brightening of the j \ 158 km line of C`. Galaxies that will evolve to a total luminosity L * \ 5 ] 1010 in L _ the current era are considered at various redshifts. When the C` luminosity is evolved in accordance with a starburst scenario, the expected spectral line antenna temperature at the focus of a 10 m telescope is about 2 mK for galaxy models at redshifts up to that at which the starburst occurs. Such a spectral line is detectable with current submillimeter wavelength instrumentation at good submillimeter-wave sites like the South Pole. If the telescope were equipped with an array receiver and wide-bandwidth spectrometers (100 channels distributed over 5 GHz), a ““ blank sky ÏÏ survey for such objects would likely detect several hundred during a winter of observation. The number and distribution of detections would provide a sensitive test of galaxy formation models, even if protogalaxies are shrouded in dust and faint at near-infrared wavelengths. Most of the energy released in the collapse of protogalaxies and the Ðrst generations of star formation may appear at Earth as submillimeter-wave radiation ; testing this hypothesis will necessarily require submillimeter-wave observations. Subject headings : early universe È galaxies : formation È infrared : galaxies È radio lines : galaxies