AAS 201st Meeting, January, 2003
Session 68. Structure of Galaxies with Central Masses
Oral, Tuesday, January 7, 2003, 2:00-3:30pm, 602-604

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[68.02] A Comparison of Estimates of the Black Hole Mass in the Maser Galaxy NGC 4258

C. Siopis, M.C. Aller (U. Michigan), R. Bender (Universitäts-Sternwarte, Germany), G. Bower (CSC, STScI), A. Dressler (Carnegie Observatories), S.M. Faber (UCO/Lick Obs., UCSC), A.V. Filippenko (U. California, Berkeley), K. Gebhardt (U. Texas), R. Green (NOAO), C. Grillmair (SIRTF Science Center), L.C. Ho (Carnegie Observatories), J. Kormendy (U. Texas), T.R. Lauer (NOAO), J. Magorrian (Dept. of Physics, U. Durham, UK), J. Pinkney (Ohio Northern Univ.), D. Richstone (U. Michigan), S. Tremaine (Princeton Univ. Obs.)

The mass of the central supermassive black hole of the SAB(s)bc galaxy NGC 4258 is determined from stellar dynamical models which use superpositions of orbits to fit photometric and kinematic data. The data include ground-based and HST/NICMOS K-band photometry as well as ground-based long-slit and HST/STIS calcium triplet spectroscopy. The data are fit to three-integral axisymmetric models using a number of plausible inclination angles, axis ratios, mass to light ratios and central point (``black hole'') masses. The combination of these parameters that best fits the data, in a \chi2 sense, then yields the ``most probable'' central black hole mass.

The findings are in agreement with the M\bullet - \sigma relation, and also with the black hole mass determination of this galaxy by Miyoshi et al. (1995) using maser observations of rotating gas at 0.15 pc from the galactic center. This is the first galaxy for which the central black hole mass has been estimated independently from maser obsevations and from stellar dynamics.

Support for this work was provided by NASA through grants from STScI which is operated by AURA, under NASA contract NAS 5-26555.

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