The disturbed Milky Way

In the past three years data from the Gaia mission has changed our view of the Milky Way. It has become clear that the motions of its stars are dramatically disturbed.

Ripples across its disc have been produced by interaction with a nearby galaxy – the Sagittarius dwarf galaxy – and the Milky Way’s bar and spiral arms push stars around the Galaxy, disrupting their original orbits. Traditional modelling techniques cannot capture this complexity.

This project will use ground-breaking techniques to explain and, for the first time, model these effects on the Milky Way.

This will result in pioneering use of Gaia data to measure the Milky Way’s gravitational field and thereby dark matter distribution.The project will be led by Dr Paul McMillan, Lund Observatory, who has expertise in dynamical modelling of the Galaxy, and knowledge of the Gaia data.

The project will first investigate the ripples caused by Sagittarius, as these are the most recently discovered and least understood of Galactic disturbances.

We will then build models using cutting edge techniques in dynamics that capture the effects of all the disturbances, and apply them to measure the gravitational field of the Milky Way with greater accuracy than ever before.The Milky Way is the only galaxy that we can study in such extraordinary detail.

The lessons we learn give us a unique insight into galaxy structure and evolution.