CO observations of luminous IR galaxies at intermediate redshift

We present new measurements of the (CO)-C-12 (J = 1-0) emission from 16 lum inous infrared galaxies (LIGs) at intermediate redshift (cz similar to 1000 0-50000 km s(-1)). These new data were selected by isolated and normal morp hology. Although there already exist measurements of CO emission from LIGs in the literature, they are mostly strongly interacting/merging systems. Th e new CO data represent an important new addition to the literature in that they both expand the relatively small number of samples of LIGs measured i n CO, and they include an interesting subset of LIGs that were selected bas ed on isolated and normal morphology. The CO observations were performed us ing the NRO 45-m telescope. From measurements of the CO emission and the IR AS database, we discuss the molecular gas and dust properties of late-type galaxies at intermediate redshift. Comparisons of the CO and dust propertie s of the new result with those from other CO measurements have revealed the characteristics of this sample: (1) It shows the deepest CO observations o f IRAS galaxies at intermediate redshift without any strong interaction fea tures. (2) It has typical properties of normal IRAS galaxies in terms of st ar-formation efficiency, color-color diagrams and galactic nuclear activity . (3) It has a smaller gas-to-dust ratio than normal IRAS galaxies. This ca n be explained by a two-component dust model; our sample consists of mostly warm dust.