AAS 205th Meeting, 9-13 January 2005
Session 118 Activity in the Nuclei of Galaxies
Oral, Wednesday, January 12, 2005, 10:00-11:30am, California

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[118.03] Gemini/GNIRS Observations of the Supermassive Black Hole in Centaurus A

J. D. Silge, K. Gebhardt (University of Texas at Austin), M. Bergmann (NOAO Gemini Science Center), D. Richstone (University of Michigan)

The infrared spectrograph GNIRS on Gemini South unlocks new possibilities to study the central black holes in dusty galaxies that have been inaccessible to previous black hole studies. We exploit good near-infrared seeing to measure the central black hole of Cen A (NGC 5128). We measure the stellar kinematics of NGC 5128 using the region around the CO bandheads at 2.3 microns and determine the black hole mass using orbit-based models. Black holes are believed to be essential components of galaxies, and their evolutionary states appear to be closely linked to those of their hosts. However our knowledge does not go much beyond this; none of the many theoretical models that predict a correlation between a black hole and its host have been excluded with current data. NGC 5128 will play an important role in helping the situation; it has an active nucleus with a black hole that is currently being fed and it is the nearest giant elliptical galaxy. However, the very characterstics which make this galaxy so interesting have also been serious roadblocks to more detailed knowledge. NGC 5128 contains large amounts of dust which hamper optical spectroscopy, especially in the central regions which are so critical for accurately measuring the black hole mass. Our observational treatment opens up a new avenue for black hole research as it allows us to probe the most interesting galaxies; NGC 5128 is the prime example.

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© 2004. The American Astronomical Society.