Warm molecular gas in nearby galaxies. Mapping of the CO(3-2) emission

Using the Heinrich-Hertz-Telescope on Mt. Graham, Arizona, we have observed several nearby galaxies in the CO(3-2) line. The CO(3-2) emission traces - in contrast to lower rotational transitions - a warmer and denser component of the molecular gas. We find that this emission is spatially extended in the target galaxies. The excitation conditions seem to vary with the location of the gas within the galaxy, and also with the overall properties of the target objects. However, a clear correlation between the CO(3-2) emission and other quantities, such as Hubble type or IR luminosity, is not present.