- [*] On the stellar kinematical evidence for massive black holes
in galactic nuclei expected with HST
- van der Marel R.P.
- ApJ Letters, 432, L91-L94, 1994
- © 1994. The American Astronomical Society.
All Rights Reserved.
this paper in the ADS
The central line-of-sight velocity distribution, or `velocity profile'
(VP), of a stellar system with a massive central black hole has more
extended wings than a Gaussian. The importance of these wings is
studied for the high spatial resolution absorption line spectra that
are now being obtained with HST. As an example, the central VP is
calculated for an isotropic dynamical model for M87 with a 5 x 10^9
solar mass black hole, for observations through a small circular
aperture of diameter D. Conventional techniques for the analysis of
galaxy spectra that assume Gaussian VPs strongly underestimate the
true velocity dispersion (for D = 0.1 arcsec, by more than a factor
2). At HST resolution it is thus essential to model VP deviations from
a Gaussian. An actual VP shape measurement will strongly constrain any
dynamical model, but might be difficult to obtain in practice.
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