CO Observations of Nearby Active Galaxies

Summary

ABSTRACT

Southern nearby active and starburst galaxies are being mapped in the ¹²CO(1-0) and ¹²CO(2-1) lines with the SEST telescope in order to investigate possible peculiarities in the dynamics, content and distribution of the gas which could lead to one or another type of activity, as was proposed by some recent models. Large-scale stellar bars, rings or closely interacting companions seem to be present in most active galaxies, being obviously related with the mechanism of gas transport from the disc into the nuclear or circumnuclear regions. But given that many of the barred or interacting galaxies do not show enhanced nuclear activity, other relevant parameters must exist, like the total gas content, the strength of the bar, or the impact parameters of the interactions. A signature of these processes would also be nuclear elongated features or “mini-bars” that are being observed in many galaxies, mainly in the infrared. We present CO data obtained for five active interacting and barred galaxies: NGC 134, NGC 986, NGC 4027, IC 1623 and IC 2554.

We mapped the nearby starburst and active galaxies described in Table 1 in the ¹²CO(1-0) and ¹²CO(2-1) lines with the 15m SEST telescope, with resolutions of 45″ and 22″ respectively. The galaxies in our sample were selected for their angular size, morphology and significant FIR luminosity, which is an indication of their activity. All the galaxies studied happen to have companions, sometimes clearly interacting.