Velocity distributions in spherical elliptical galaxies. II. Measuring line-of-sight stellar velocity distributions.
Abstract
In this paper we look at the problem of recovering the line-of- sight velocity distribution from the integrated spectra of the halos of giant elliptical galaxies. In particular, we will be studying the measurement of tangential velocity anisotropy. The method we present is an extension of the Sargent et al. (1977, SSBS) Fourier quotient method, which is widely used for velocity dispersion and redshift measurements. We have observed NGC 1399 and NGC 1404 in Fornax and M87 and M49 in Virgo. Spectra were obtained at approximately 1 Repsilon for each galaxy. The observed line-of-sight velocity distribution of each of these systems is shown to be gaussian and estimates of the confidence levels are given. The method is effective in measuring the line-of-sight velocity distributions in nearly spherical systems at low surface brightness.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- February 1993
- Bibcode:
- 1993A&A...268..443W
- Keywords:
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- Elliptical Galaxies;
- Galactic Halos;
- Velocity Distribution;
- Absorption Spectra;
- Computational Astrophysics;
- Power Spectra;
- Red Shift;
- Stellar Spectra;
- Astrophysics