BIMA Millimeter-Wave Observations of the Core-Jet and Molecular Gas in the FR I Radio Galaxy NGC 3801

We present BIMA 3 mm observations of the radio continuum source and the molecular gas disk in the radio-loud Fanaroff and Riley type I (FR I) galaxy NGC 3801. We have detected a continuum source in the nucleus and determined that it has a flat millimeter-wave spectrum, suggesting that the emission is nonthermal and due to an AGN; the radio core is not evident in existing VLA observations. We also map the extended 3 mm emission from the previously known radio jets. In addition, we detect CO (1-0) emission associated with the dust disk observed in previous HST images. A velocity gradient is observed, indicating a 2 kpc radius rotating gas ring or disk oriented roughly perpendicular to the radio jets. The inferred molecular gas mass of the disk is M(H2) = 3 × 108 M☉, about 1% of the dynamical mass. We also find a ~108 M☉ molecular gas clump not associated with the gas disk. There is evidence that this gas is associated with a merger and is infalling. This suggests that FR I activity is related to merger activity, as is thought to be the case for FR II radio galaxies. We also find indications that one of the radio jets is entraining gas from the infalling molecular gas.