Astronomy and Astrophysics – Astrophysics
Scientific paper
1994-10-07
Astronomy and Astrophysics
Astrophysics
14 pages, 9 figures, uuencoded compressed ps file (468k), Ref: OUTP-94-04A
Scientific paper
A technique for the construction of axisymmetric distribution functions for individual galaxies is presented. It starts from the observed surface bright- ness distribution, which is deprojected to gain the axisymmetric luminosity density, from which follows the stars' gravitational potential. After adding dark mass components, such as a central black hole, the two-integral distribu- tion function (2I-DF) f(E,Lz), which depends only on the classical integrals of motion in an axisymmetric potential, is constructed using the Richardson- Lucy algorithm. This algorithm proved to be very efficient in finding f(E,Lz) provided the integral equation to be solved has been properly modified. Once the 2I-\df\ is constructed, its kinematics can be computed and compared with those observed. Many discrepancies may be remedied by altering the assumed inclination angle, mass-to-light ratio, dark components, and odd part of the 2I-DF. Remaining discrepancies may indicate, that the distribution function depends on the non-classical third integral, or is non-axisymmetric. The method has been applied to the nearby elliptical galaxy M32. A 2I-DF with ~55 degrees inclination and a central black hole (or other compact dark mass inside ~1pc) of 1.6-2*10^6 Msun fits the high-spatial-resolution kinema- tic data of van der Marel et al. remarkably well. 2I-DFs with a significantly less or more massive central dark mass or with edge-on inclination can be ruled out for M32. Predictions are made for HST-observations: spectroscopy using its smallest square aperture of 0.09"*0.09" should yield a non-gaussian central velocity profile with broad wings, true and gaussian-fit velocity dispersion of 150-170km/s and 120-130km/s, respectively.
No associations
LandOfFree
Modelling Galaxies with f(E,Lz); a Black Hole in M32 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Modelling Galaxies with f(E,Lz); a Black Hole in M32, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Modelling Galaxies with f(E,Lz); a Black Hole in M32 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-707262