This paper summarizes all presently available J_upp_>=5 ^13^CO and accompanying ^12^CO measurements of galaxy centers including new J=6-5 ^13^CO and ^12^CO observations of eleven galaxies with the Atacama Pathfinder EXperiment (APEX) telescope and also Herschel high-J measurements of both species in five galaxies. The observed J=6-5/J=1-0 ^12^CO integrated temperature ratios range from 0.10 to 0.45 in matching beams. Multi-aperture data indicate that the emission of ^13^CO(6-5) is more centrally concentrated than that of ^12^CO(6-5). The intensities of ^12^CO(6-5) suggest a correlation with those of HCO+ but not with those of HCN. The new data are essential in refining and constraining the parameters of the observed galaxy center molecular gas in a simple two-phase model to approximate its complex multi-phase structure. In all galaxies except the Seyfert galaxy NGC 1068, high-J emission from the center is dominated by a dense (n~10^5^cm^-3^) and relatively cool (20-60K) high-pressure gas. In contrast, the low-J lines are dominated by low-pressure gas of a moderate density (n~10^3^cm^-3^) and more elevated temperature (60-150K) in most galaxies. The three exceptions with significant high-pressure gas contributions to the low-J emission are all associated with active central star formation.

Cone search capability for table J/A+A/691/A289/table2 (galaxies)

Cone search capability for table J/A+A/691/A289/list (List of fits ^12^CO(6-5) and ^13^CO(6-5) spectra)