MOLECULAR GAS IN ELLIPTICAL GALAXIES WITH DUST LANES

We have searched for CO(1-0) line emission in eight dust lane elliptical and lenticular galaxies using the Nobeyama 45 m telescope. Five of the eight galaxies, including the well-studied elliptical NGC 1052, have CO emission at above the 5sigma level, with inferred molecular gas masses ranging from 10(8) to a few times 10(9) M .. Our selection criterion differs from previous surveys in that it does not depend on the far-infrared fluxes, and thus is less sensitive to the sizes and distances of the host galaxies or to the degree to which dust is heated. The relatively high detection rate of CO in these ellipticals suggests a close correlation between molecular mass and cold dust. Compared with previously studied samples of far-infrared selected early-type galaxies, our sample has on average four times more CO emission per unit far-infrared (40-120 mum) luminosity. If the intrinsic gas-to-dust ratio of these galaxies as similar to that of the Milky Way, then only about 5% of the dust mass in dust lane ellipticals radiates substantially at 60 and 100 mum, and the remaining dust must be colder than T approximately 30 K.