Axisymmetric, ThreeIntegral Models of Galaxies: A Massive Black Hole in NGC 3379
Abstract
We fit axisymmetric threeintegral dynamical models to NGC 3379 using the lineofsight velocity distribution obtained from Hubble Space Telescope FOS spectra of the galaxy center and groundbased longslit spectroscopy along four position angles, with the light distribution constrained by WFPC2 and groundbased images. We have fitted models with inclinations from 29 deg (intrinsic galaxy type E5) to 90 deg (intrinsic E1) and black hole masses from 0 to 10^{9} M_{solar}. The bestfit black hole masses range from 6x10^{7} to 2x10^{8} M_{solar}, depending on inclination. The preferred inclination is 90 deg (edgeon) however, the constraints on allowed inclination are not very strong, owing to our assumption of constant M/L_{V}. The velocity ellipsoid of the best model is not consistent with either isotropy or a twointegral distribution function. Along the major axis, the velocity ellipsoid becomes tangential at the innermost bin, radial in the midrange radii, and tangential again at the outermost bins. The rotation rises quickly at small radii owing to the presence of the black hole. For the acceptable models, the radialtotangential [(σ^{2}_{θ}+σ^{2}_{φ})/2] dispersion in the midrange radii ranges over 1.1<σ_{r}/σ_{t}<1.7, with the smaller black holes requiring larger radial anisotropy. Compared with these threeintegral models, twointegral isotropic models overestimate the black hole mass since they cannot provide adequate radial motion. However, the models presented in this paper still contain restrictive assumptionsnamely, assumptions of constant M/L_{V} and spheroidal symmetryrequiring yet more models to study black hole properties in complete generality.
 Publication:

The Astronomical Journal
 Pub Date:
 March 2000
 DOI:
 10.1086/301240
 arXiv:
 arXiv:astroph/9912026
 Bibcode:
 2000AJ....119.1157G
 Keywords:

 GALAXIES: ELLIPTICAL;
 GALAXIES: INDIVIDUAL (NGC 3379);
 GALAXIES: KINEMATICS AND DYNAMICS;
 GALAXIES: NUCLEI;
 Astrophysics
 EPrint:
 15 pages, emulateapj sty, accepted for publication in The Astronomical Journal