We report D1A resolution K-band (2 km) imaging spectroscopy of the central parsec of our Galaxy. The derived radial velocities for 223 early-and late-type stars probe the nuclear mass distribution to spatial scales of 0.1 pc. We Ðnd a statistically very signiÐcant increase of projected stellar velocity dispersion from about 55 km s~1 at p D 5 pc to 180 km s~1 at p D 0.1 pc. The stars are also rotating about the dynamic center. The late-type stars follow general Galactic rotation, while the early-type stars show counter-rotation. Fitting simultaneously the observed projected surface densities and velocity dispersions, we derive the intrinsic volume densities and radial velocity dispersions as a function of distance from the dynamic center for both types of stars. We then derive the mass distribution between 0.1 and 5 pc from the Jeans equation assuming an isotropic velocity Ðeld. Our analysis requires a compact central dark mass of 2.5È3.2 ] 106 at 6È8 p signiÐcance. The dark mass has a density of 109 pc~3 or M _ , M _ greater and a mass to 2 km luminosity of º 100. The increase in mass-to-luminosity ratio can be reduced but not eliminated even if extreme anisotropic velocity destributions are considered. The dark mass cannot be a cluster of solar mass remnants (such as neutron stars). It is either a compact cluster of 10È20 black holes or a single massive black hole. M _

No abstract

No abstract

No abstract

We present high angular resolution (0".15-0".5) near infrared images and spectroscopy of the Circinus galaxy, the closest Seyfert 2 galaxy known. The data reveal a non-stellar nuclear source at 2.2 microns. The coronal line region and the hot molecular gas emission extend for 20-50 pc in the ionization cone. The data do not show evidence for a point-like concentration of dark mass; we set an upper limit of 4*10^6 Mo to the mass of a putative black hole. We find evidence for a young nuclear stellar population, with typical ages between 4*10^7 and 1.5*10^8 yrs. The luminosity of the starburst inside a few hundred pc is comparable to the intrinsic luminosity of the Seyfert nucleus, and the two of them together account for most of the observed bolometric luminosity of the galaxy. Within the central 12 pc the starburst has an age of about 7*10^7 yrs and radiates about 2% of the luminosity of the active nucleus. We discuss the implications of these results for models that have been proposed for the starburst-AGN connection.Comment: 44 pages, Latex (including 11 Figures), Color Figures 1, 2 and 4 are available at http://www.arcetri.astro.it/~maiolino/ , ApJ in pres