A New Mass Modelling Trick

Extract

The estimation of the distribution of the total (luminous and dark) mass in early type systems is hard! Even for the lucky few systems for which kinematic information is available, its implementation is mired in problems, given uncertainties about the assumptions that enter the calculations; the most critical of such assumptions involve considerations of the system geometry and the shape of its velocity ellipsoid. This work offers an independent means of getting to the mass distributions of early type galaxies, without relying directly on the phase space distribution function. The methodology is based upon the well established idea that in elliptical galaxies, the largest variations in normalised velocity dispersion profiles occur typically at R < 0.5R_e (R_e≡ half-light radius) and at R ≥ 2R_e.