Year: 2008
Type: article
Abstract: NGC 5128 is a well-studied elliptical galaxy with an excellent kinematic data set for planetary nebulae that has been modeled up until now only by solving the Jeans equation for spherical systems. As a first approximation beyond spherical symmetry, we model the galaxy as an axisymmetric system flattened by rotation with isotropic velocity distribution. We propose a new version of such an isotropic rotator having a cuspy density profile with NFW-like behavior. The solutions of the Jeans equations for a single component of such form do not reproduce the data well: the rotation curve rises too slowly with radius, and the velocity dispersion profile drops too fast. The data are well fitted, however, by a system built with two components: a more compact, flattened, less massive, fast-rotating and cold "bulge" and an extended, almost spherical, more massive, slow-rotating, and hot "halo." This picture agrees well with the results of recent N -body simulations of galaxy mergers, which tend to produce oblate rotating spheroids. The total mass of the system is estimated to be (9.1 ± 3.5) × 10 11 solar masses, and the mass-to-light ratio is only 26 ± 17 solar units.
Source: The Astrophysical Journal
DOI: 10.1086/589943
Author: Ewa L. Łokas
Institution: Nicolaus Copernicus Astronomical Center
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2079518577