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F. D. Macchetto (Space Telescope Science Institute & ESA)
There is increasing evidence for the existence of supermassive black holes at the centers of all galaxies, and much work is being devoted to understand the processes that lead to their formation ,the duty cycle for the active phase of these black holes and the relevant fueling mechanisms .
I will review some of our recent results in this area ,in particular the direct evidence for the presence of supermassive black holes at the center of nearby Seyfert galaxies determined by HST high spatial resolution observations of the kinematics of the central regions. The study of the gas kinematics provides a unique tool to probe the gravitational potential of the nuclear regions of Seyfert galaxies down to a limit radius of a few parsecs. This is particularly important to detect and measure the mass associated with any central massive black hole.
We have obtained high spatial resolution spectra of a number of Seyfert galaxies ,with the STIS G430M and G750M gratings , and we have been able to separate the emission line components associated with different velocity systems. We have derived two-dimensional velocity fields and determined the mass of the central black hole with good precision for each of the galaxies.