1994A&A...288L..41W

A sensitive search for millimeterwave CO emision in 8 damped Lyman-α systems, 3 heavy element absorption line systems and one emission line galaxy, at redshifts ranging from 0.5 to 2.8, have yielded upper limits to the amount of molecular gas. The limits still allow relatively high H₂ masses, but our results show that damped Lyman-α systems are not similar to the hyperluminous infrared galaxies at high redshits found in the IRAS database. One tentative detection of CO emission at z_a=2.47 remains, but is very uncertain. We are not able to confirm a claimed detection of CO emission at z_a=2.14 towards Q0528-250.