NASONOVA O.G., DE FREITAS PACHECO J.A. and KARACHENTSEV I.D.
Abstract (from CDS):
This work aims to provide a new mass estimate for the Fornax cluster and the Fornax-Eridanus complex, avoiding methods like the virial or fits of the X-ray emission profile, which assume that the system is in equilibrium. This is probably not the case for Fornax, because it is still in process of formation. Our mass estimate is based on determination of the zero-velocity surface, which, in the context of the spherical infall model, permits an evaluation of the total mass inside such a surface. The zero-velocity surface radius R0 was estimated either by a running median procedure or by fitting the data to the velocity field expected from the spherical model, including effects of the cosmological constant. The velocity field in a region within 20Mpc of the Fornax center was mapped using a list of 109 galaxies whose distances have an average accuracy of 0.31mag in their distance modulus. Our analysis indicates that the mass of the Fornax cluster itself is [0.40-3.32]x1014M☉ inside a radius of [2.62-5.18]Mpc while the mass inside [3.88-5.60]Mpc, corresponding to the Fornax-Eridanus complex, is [1.30-3.93]x1014M☉.