Estimation of distances within the Milky Way using tidal streams

TL;DR

This paper evaluates a method for estimating distances within the Milky Way using tidal streams, demonstrating its effectiveness with noise-free data and discussing limitations when observational errors are included.

Contribution

It applies and tests a technique for constraining the Galactic potential and distances using tidal streams, highlighting its accuracy and limitations under realistic conditions.

Findings

Excellent discrimination against incorrect potentials in noise-free data

Accurate prediction of heliocentric distances in ideal conditions

Constraints on the distance of streams despite observational errors

Abstract

During the past 20 years, numerous stellar streams have been discovered in both the Milky Way and the Local Group. These streams have been tidally torn from orbiting systems, which suggests that most of them should roughly trace the orbit of their progenitors around the Galaxy. As a consequence, they play a fundamental role in understanding the formation and evolution of our Galaxy. This project is based on the possibility of applying a technique developed by Binney in 2008 to various tidal streams and overdensities in the Galaxy. The aim is to develop an efficient method to constrain the Galactic gravitational potential, to determine its mass distribution, and to test distance measurements. Here we apply the technique to the Grillmair & Dionatos cold stellar stream. In the case of noise-free data, the results show that the technique provides excellent discrimination against incorrect potentials and that it is possible to predict the heliocentric distance very accurately. This changes dramatically when errors are taken into account, which wash out most of the results. Nevertheless, it is still possible to rule out spherical potentials and set constraints on the distance of a given stream.