NGC 5128 as an isotropic rotator

Abstract

NGC 5128 is a well-studied elliptical galaxy with an excellent kinematic data set for planetary nebulae which has been modelled up till 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 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) x 10^11 solar masses and the mass-to-light ratio is only 26 +/- 17 solar units.

4 pages, 3 figures, revised version accepted for publication in ApJ Letters

References in corpus (15)

• A Universal Density Profile from Hierarchical Clustering
• Kinematic Structure of Merger Remnants
• Properties of spherical galaxies and clusters with an NFW density profile
• Centaurus A - NGC 5128
• Dark matter in elliptical galaxies: II. Estimating the mass within the virial radius
• Dark matter distribution in the Coma cluster from galaxy kinematics: breaking the mass-anisotropy degeneracy
• Observing the dark matter density profile of isolated galaxies
• Lost & Found Dark Matter in Elliptical Galaxies
• The Mass-To-Light Function of Virialized Systems and the Relationship Between Their Optical and X-ray Properties
• The distance to the giant elliptical galaxy NGC 5128
• The Planetary Nebula System and Dynamics in the Outer Halo of NGC 5128
• Dark matter in elliptical galaxies: I. Is the total mass density profile of the NFW form or even steeper?
• Mass distribution in nearby Abell clusters
• The Formation of Disks in Elliptical Galaxies
• The importance of interloper removal in galaxy clusters: saving more objects for the Jeans analysis

Cited by in corpus (3)

• The Lost Dwarfs of Centaurus A and the Formation of its Dark Globular Clusters
• Devouring The Centaurus A Satellites: Modeling Dwarf Galaxies with Galacticus
• Axion-like particle searches with MeerKAT and SKA