The mass of the Milky Way and M31 using the method of least action

TL;DR

This paper estimates the masses of the Milky Way and M31 using the Numerical Action Method, incorporating satellite motions to refine mass ranges and validating results with simulated galaxy catalogs.

Contribution

It introduces an application of NAM to constrain galaxy masses using satellite motions and validates the approach with simulations.

Findings

Mass range for MW: 1.5-4.5 x 10^12 M_sun

Mass range for M31: 1.5-5.5 x 10^12 M_sun

Method consistent with simulated galaxy halo masses

Abstract

We constrain the most likely range of masses for the Milky Way and M31 using an application of the Numerical Action Method (NAM) that optimizes the fit to observed parameters over a large ensemble of NAM-generated solutions. Our 95% confidence level mass ranges, 1.5-4.5 x 10^12 m_sun for MW and 1.5-5.5 x 10^12 m_sun for M31, are consistent with the upper range of estimates from other methods and suggests that a larger proportion of the total mass becomes detectable when the peculiar motions of many nearby satellites are taken into account in the dynamical analysis. We test the method against simulated Local Group catalogs extracted from the Millennium Run to confirm that mass predictions are consistent with actual galaxy halo masses.