Journal Article

Estimating black hole masses in triaxial galaxies

Remco C. E. van den Bosch and P. Tim de Zeeuw

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 401, issue 3, pages 1770-1780
Published in print January 2010 | ISSN: 0035-8711
Published online January 2010 | e-ISSN: 1365-2966 | DOI:
Estimating black hole masses in triaxial galaxies

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Most of the supermassive black hole mass (M) estimates based on stellar kinematics use the assumption that galaxies are axisymmetric oblate spheroids or spherical. Here, we use fully general triaxial orbit-based models to explore the effect of relaxing the axisymmetric assumption on the previously studied galaxies M32 and NGC 3379. We find that M32 can only be modelled accurately using an axisymmetric shape viewed nearly edge-on, and our black hole mass estimate is identical to previous studies. When the observed 5° kinematical twist is included in our model of NGC 3379, the best shape is mildly triaxial, and we find that our best-fitting black hole mass estimate doubles with respect to the axisymmetric model. This particular black hole mass estimate is still within the errors of that of the axisymmetric model and consistent with the M–σ relationship. However, this effect may have a pronounced impact on black hole demography, since roughly a third of the most massive galaxies are strongly triaxial.

Keywords: black hole physics; galaxies: elliptical and lenticular, cD; galaxies: individual: NGC 3379; galaxies: individual: M32; galaxies: kinematics and dynamics; galaxies: nuclei; galaxies: structure

Journal Article.  8031 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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