The Mass Profile of NGC 3268 from Its Stellar Kinematics

The mass profile of the central galaxy of the Antlia cluster, NGC 3268, is studied through a spherical Jeans analysis, combined with a Bayesian approach. The prior distributions are derived from dark matter simulations. The observational dataset consists of Gemini/GMOS multi-object spectra observed from several programmes, supplemented with the kinematics of a small sample of globular clusters from the literature. An NFW mass profile and several options of constant anisotropy are considered. The analysis indicates a moderately massive halo, with a virial mass of (1.4 – 4.3) × 1013M⊙, depending on the assumed anisotropy. A comparison with the kinematics of the galaxy population from the Antlia cluster suggests that a fraction of galaxies is not yet virialised and may currently be infalling into the cluster.