Made-to-measure galaxy models - II Elliptical and Lenticular Galaxies

TL;DR

This study compares made-to-measure and Schwarzschild dynamical models for elliptical and lenticular galaxies, showing strong agreement in mass-to-light ratios and anisotropy parameters, and demonstrates the effectiveness of the M2M method.

Contribution

It provides the largest comparative analysis of M2M and Schwarzschild methods for galaxy modelling, validating M2M's accuracy in dynamical parameter estimation.

Findings

Over 80% of M/L ratios differ by less than 10% between methods

More than 95% differ by less than 20%

M2M and Schwarzschild models yield similar anisotropy parameters

Abstract

We take a sample of 24 elliptical and lenticular galaxies previously analysed by the SAURON project using three-integral dynamical models created with Schwarzschild's method, and re-analyse them using the made-to-measure (M2M) method of dynamical modelling. We obtain good agreement between the two methods in determining the dynamical mass-to-light (M/L) ratios for the galaxies with over 80% of ratios differing by < 10% and over 95% differing by < 20%. We show that (M/L)_M2M is approximately equal to (M/L)_Sch. For the global velocity dispersion anisotropy parameter delta, we find similar values but with fewer of the made-to-measure models tangentially anisotropic by comparison with their SAURON Schwarzschild counterparts. Our investigation is the largest comparative application of the made-to-measure method to date.