# Upper Limit on the Milky Way Mass from the Orbit of the Sagittarius Dwarf Satellite

## TL;DR

This paper models the orbit of the Sagittarius dwarf galaxy to estimate the Milky Way's mass, concluding it is likely less than 10^12 solar masses, which aligns with certain cosmological models.

## Contribution

It introduces a semi-analytic orbital modeling approach that constrains the Milky Way's mass using Sagittarius tidal streams, supporting lower mass estimates.

## Key findings

- Milky Way mass likely less than 10^12 solar masses
- Semi-analytic models agree with N-body simulations
- Supports lower mass estimates consistent with ΛCDM

## Abstract

As one of the most massive Milky Way satellites, the Sagittarius dwarf galaxy has played an important role in shaping the Galactic disk and stellar halo morphologies. The disruption of Sagittarius over several close-in passages has populated the halo of our Galaxy with large-scale tidal streams and offers a unique diagnostic tool for measuring its gravitational potential. Here we test different progenitor mass models for the Milky Way and Sagittarius by modeling the full infall of the satellite. We constrain the mass of the Galaxy based on the observed orbital parameters and multiple tidal streams of Sagittarius. Our semi-analytic modeling of the orbital dynamics agrees with full $N$-body simulations, and favors low values for the Milky Way mass, $\lesssim 10^{12}M_\odot$. This conclusion eases the tension between $\Lambda$CDM and the observed parameters of the Milky Way satellites.