ISM dynamics around black holes in nearby (radio) early-type galaxies with HST

The black holes (BHs) at the centers of present-day bright early-type galaxies might represent the most massive endpoints for BH growth in the Universe. The majority of these galaxies contains detectable amounts of emission-line gas at their centers which indicate that their black holes are still growing, but typically at very modest rates. The gas kinematics potentially form a valuable diagnostic of both this growth process and the gravitational potential well of the BH. Here we focus on the nuclear gas velocity dispersion which often exceeds the stellar velocity dispersion. This could be due to either the gravitational potential of the black hole or turbulence associated with the accretion process. We try to discriminate between these two scenarios.