Molecular gas in Centaurus A: the 12CO J = 2-1 map and 13CO measurements

The authors present a fully sampled map at a resolution of 22″of the 12CO J = 2-1 emission from the dust lane of Cen A and13CO J = 1-0 measurements along the major axis. The12CO J = 2-1 line is strong throughout the disk and comparable to the line strength in the center. The 12CO J =2-1/1-0 ratio is close to unity in large parts of the disk. Together with a 13CO J = 2-1/1-0 ratio of 0.9 in the disk this implies gas kinetic temperatures of 10K-20K and H2 densities of the order of 5×103cm-3 to104cm-3. The 12CO/13CO J =1-0 ratio along the major axis varies from 8 to 14