Molecular Lines as Diagnostics of High-Redshift Objects

Models are presented for CO rotational line emission by high redshiftstarburst galaxies. The influence of the cosmic microwave background on thethermal balance and the level populations of atomic and molecular species isexplicitly included. Predictions are made for the observability of starburstgalaxies through line and continuum emission between z=5 and z=30. It is foundthat the Millimeter Array could detect a starburst galaxy with ~10^5 Orionregions, corresponding to a star formation rate of about 30 Mo yr^{-1}, equallywell at z=5 or z=30 due to the increasing cosmic microwave backgroundtemperature with redshift. Line emission is a potentially more powerful probethan dust continuum emission of very high redshift objects.Comment: 15 pages LaTex, uses aasms4.sty, Accepted by ApJ