Total mass distributions of Sersic galaxies from photometry $&$ cent\ ral velocity dispersion

TL;DR

This paper introduces a new method to determine the total mass density profiles of Sersic elliptical galaxies using only surface brightness and central velocity dispersion, applicable to distant galaxies.

Contribution

It presents a novel approach to derive galaxy mass profiles from minimal data, combining deprojection, a step-function M/L ratio, and smoothing techniques, validated on real galaxy data.

Findings

Successfully applied to NGC 3379 and NGC 4499

Accurately recovers mass profiles out to 3 effective radii

Demonstrates method's robustness with simulated and real data

Abstract

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 $\sigma_0$. 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 ($M/L$). The resulting raw, discontinuous, total, 3-D mass density profile is then smoothed according to a proposed smoothing prescription. The parameters of this raw $M/L$ are characterised by implementing the observables in a model-based study. The complete characterisation of the formalism is provided as a function of the measurements of the brightness distribution and $\sigma_0$. 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.