Dust and CO emission towards the centers of normal galaxies, starburst galaxies and active galactic nuclei

Abstract

Aims. The amount of interstellar matter in a galaxy determines its evolution, star formation rate and the activity phenomena in the nucleus. We therefore aimed at obtaining a data base of the 12 CO line and thermal dust emission within equal beamsizes for galaxies in a variety of activity stages. Methods. We have conducted a search for the 12 CO (1–0) and (2–1) transitions and the continuum emission at 1300 µ mt owards the centers of 88 galaxies using the IRAM 30 m telescope (MRT) and the Swedish ESO Submillimeter Telescope (SEST). The galaxies are selected to be bright in the far infrared (S 100 µm > 9 Jy) and optically fairly compact (D25 ≤ 180 �� ). We have applied optical spectroscopy and IRAS colours to group the galaxies of the entire sample according to their stage of activity into three sub-samples: normal, starburst and active galactic nuclei (AGN). The continuum emission has been corrected for line contamination and synchrotron contribution to retrieve the thermal dust emission. For the latter we have determined the radio spectral indices of the individual sources and extrapolated the synchrotron emission corresponding to our millimeter beams to 1300 µm. Results. We present new observational data for the 12 CO (1–0) and (2−1) transitions and the thermal dust emission at 1300 µm for 88 galaxies. In conjunction with our previous data, the new observations are used to compile an updated catalogue for a total of 160 galaxies.