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C.G. Mundell (Astrophysics Research Institute, JMU), P. Ferruit (Observatoire de Lyon), N. Nagar (Osservatorio Astrofisico di Arcetri), A.S. Wilson (University of Maryland)
It has been suggested that the central regions of many galaxies are unlikely to be in a static steady state, with instabilities caused by sinking satellites, the influence of a supermassive black hole or residuals of galaxy formation, resulting in the nuclear black hole orbiting the galaxy center. The observational signature of such an orbiting black hole is an offset of the active nucleus (AGN) from the kinematic center defined by the galaxy rotation curve. This orbital motion may provide fuel for the AGN, as the hole `grazes' on the ISM, and bent radio jets, due to the motion of their source.
The early type (E/SO) Seyfert galaxy, NGC2110, with its striking twin, `S'-shaped radio jets, is a unique and valuable test case for the offset-nucleus phenomenon since, despite its remarkably normal rotation curve, its kinematically-measured mass center is displaced both spatially (260 pc) and kinematically (170 km s-1) from the active nucleus located in optical and radio studies. However, the central kinematics, where the rotation curve rises most steeply, have been inaccessible with ground-based resolutions. We present new, high resolution WFPC2 imaging and long-slit STIS spectroscopy of the central 300 pc of NGC2110. We discuss the structure and kinematics of gas moving in the galactic potential on subarcsecond scales and the reality of the offset between the black hole and galaxy mass center.