Publications
of the
MPIfR
Optical & Infrared
Interferometry Group
M. Wittkowski and W.J. Duschl:
Determination of the Mass Distribution in
Galactic Centers
New Astronomy 4, 543-555 (1999)
Abstract.
We investigate how well one can determine the gravitational
potential in galactic centers from an analysis of the observed
line-of-sight velocities of interstellar material, e.g. (giant)
molecular clouds. In this paper, we aim to demonstrate the
principle of our approach. Therefore, we use simulated sets of
data. We model the mass distribution as a combination of a
point-like central mass and an extended component. We calculate the
observable distribution of line-of-sight velocities in the
corresponding gravitational potential for different global flow
patterns (purely circular motion, accretion disks, in- and
outflows). We fit this data to previously unknown flow patterns and
determine the degree of accuracy of the mass parameters by means of
a Monte Carlo technique. We find that the best fit mass parameters
typically differ from the true parameters by factors of 1 to 5 (with
mass-parameters as expected for Seyfert Galaxies, a spectral
resolution of 20 km/sec, and a spatial distribution of 50
observed clouds within 300 pc), in some cases even more.
This implies that, in addition to purely circular motion, other flow
patterns should be considered when interpreting real data.
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