1997A&A...322..419W

We present a fully sampled map of the ¹³CO J=1-0 emission in the dust lane of Centaurus A as well as ¹³CO 2-1 and for the first time C¹⁸O 1-0 spectra at selected positions. The morphology of the ¹³CO map is similar to the ¹²CO 1-0 and 2-1 maps. Maps of the ¹²CO 2-1/1-0 and ¹²CO/¹³CO 1-0 ratios show small variations of the ratios throughout the disk with a rise of the ¹²CO 2-1/1-0 ratio towards the southeast. The values found are within the range as found in other galaxies. Radiative transfer calculations indicate a kinetic temperature of 10-15K and H₂ densities on the order of 3x10⁴cm^–3. In the southeastern part of the dust lane, the gas appears to be warmer (20-30K) which may be due to a greater star formation activity. The total molecular mass is about 1.2 x 10⁸M_☉. The observed ¹²CO 2-1 intensity is consistent with the molecular gas being distributed in a thin, warped disk as modelled by Quillen et al. (1992ApJ...391..121Q). Comparison of the measurements with the kinematic model shows good agreement.