I'm a researcher at the Institute for Astronomy, part of the Royal Observatory of Edinburgh and the University of Edinburgh. I'm interested in how bodies move and interact in and around galaxies -- primarily our own Milky Way.

My work is framed by a desire to understand the nature of dark matter through its inferred and measured structure and properties.

I am also excited about developing numerical techniques, including machine learning.

I can be reached at michael.petersen@roe.ac.uk.

Research Overview

Milky Way-Large Magellanic Cloud interation. Milky Way secular evolution, velocity fields in barred galaxies, structure formation in barred galaxies. Mock stellar catalogs. Dark matter halo dynamics. High precision n-body simulations. Numerical techniques.

Recent Work: The Large Magellanic Cloud

Recently, I have been working on the observable effects of the Large Magellanic Cloud on the stellar halo of the Milky Way. With Jorge Peñarrubia, I made predictions for the observable (apparent) dipole signature in the halo resulting from the motion of the disc. We then detected the dipole signature in a sample of distant halo tracers. Click here for more details about the project and a selection of the press coverage.

Barred Galaxies

Bars are the most ubiquitous non-axisymmetric structure observed in the local universe, observed in roughly two-thirds of local galaxies. My thesis focused on numerical simulations and analytic calculations to examine detailed physical processes related to the formation and evolution of bars.

One result to come of this work is the discovery of a trapped component in the dark matter halo that mimics the stellar bar, which we refer to as the shadow bar. Click on the image below for a more comprehensive look at the shadow bar work, or read the MNRAS paper.

The shadow bar has consequences for the structure of the dark matter halo at the solar circle.

The combination of the stellar and shadow bar drives non-axisymmetric structure in the dark matter halo--which has consequences for direct detection experiments on Earth. Click on the image below for a more comprehensive look at the implications for direct detection experiments, or read the PhysRevD paper.


I'm part of the team organising the seminar series at the Royal Observatory. I also organise the Local Universe Reading group, a collection of four research teams at the ROE. I organise the Equality, Diversity, and Inclusion group at the IfA. If you are interested in taking part in any of the groups, please contact me!


Published work.


See what I'm up to on Github.


I'm also on Twitter.