Total mass distributions of Sersic galaxies from photometry and central velocity dispersion

¹ School of Physics & Astronomy, University of Nottingham, Nottingham NG7 2RD, UK e-mail: dalia.chakrabarty$@$nottingham.ac.uk
² Institute for Astronomy, University of Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK e-mail: bmj@roe.ac.uk

Received: 14 April 2008
Accepted: 7 February 2009

Abstract

Aims. We develop a novel way of finding total mass density profiles in Sersic ellipticals, to about 3 times the major axis effective radius, using no other information other than what is typically available for distant galaxies, namely the observed surface brightness distribution and the central velocity dispersion .

Methods. The luminosity density profile of the observed galaxy is extracted by deprojecting the measured brightness distribution and scaling it by a fiduciary, step-function shaped, raw mass-to-light ratio profile (). The resulting raw, discontinuous, total, 3-D mass density profile is then smoothed according to a proposed smoothing prescription. The parameters of this raw are characterised by implementing the observables in a model-based study.

Results. The complete characterisation of the formalism is provided as a function of the measurements of the brightness distribution and . The formalism, thus specified, is demonstrated to yield the mass density profiles of a suite of test galaxies and is successfully applied to extract the gravitational mass distribution in NGC 3379 and NGC 4499, out to about 3 effective radii.