The Nuclear Gasdynamics and Star Formation of NGC 7469

We report interferometric radio CO2-1 observations at a resolution of 0.7",and 0.085" resolution adaptive optics K-band spectroscopy of the inner fewarcseconds of NGC7469. The CO2-1 map shows a ring of molecular clouds and abright extended nucleus, with a bar or pair of spiral arms between them. Thedynamical structure of both the radio CO2-1 and the K-band H2 1-0S(1) lines canbe reproduced using an axisymmetric mass model comprising 3 components: a broaddisk, a ring 4-5" across, and an inner nuclear ring about 0.5" across. Nonon-circular motions faster than the velocity residuals of 25 km/s are seen,although this may be because in some cases a secondary bar is not expected tocause gas inflow. From the dynamical mass and estimates of the stellar mass wefind that the CO-to-H_2 conversion is 0.4-0.8 times that for the Milky Way. TheH2 1-0S(1) morphology peaks at the nucleus, although there is no strong nuclearmass concentration. The 1-0S(1) is likely to originate in X-ray of gas by theAGN rather than via star formation. Using the 2.3um stellar CO2-0 absorptionand the continuum slope we have directly resolved the nuclear star cluster tobe 0.15-0.20" across, and find that it is asymmetric. This cluster has an ageof less than about 60Myr and contributes 20-30% of the nuclear K-band light,and about 10% of the nuclear bolometric luminosity. Within a radius of ~4" gascontributes more than half the total mass; but in the nucleus, within a radiusof 0.1", it is likely that most of the mass is due to starsComment: accepted for publication in ApJ (see their pages for a version with higher quality figures