Dr Paul McMillan

I am an astrophysicist who studies the dynamics of galaxies, particularly our own Milky Way. I have worked on building theoretical, but observationally motivated, models of the Milky Way and the orbits of its stars. I have also worked in data processing for the Gaia mission and the RAVE spectroscopic survey. I am working to understand what Gaia and other surveys are telling us about the Milky Way, and to produce the science case for a future GaiaNIR astrometric mission.

I am a lecturer at the University of Leicester. Until summer 2023 I was an associate professor and lecturer at Lund Observatory, where I was part of the Gaia group. Before that I was a postdoctoral researcher at the University of Oxford working with Prof James Binney in the Galactic Dynamics group. I did my PhD in the Theoretical Astrophysics group here at the University of Leicester supervised by Prof. Walter Dehnen. This included a Marie Curie student fellowship in Marseille with Lia Athanassoula.

My dynamical modelling research is dominated by the study of the Milky Way, and how best to interpret and exploit the enormously rich but confusing data we are gaining from numerous large surveys, especially Gaia.

In particular I'm focused on producing dynamical models which can be compared to observations of the Milky Way, as it's only through understanding the Galaxy's dynamics that we will be able to discover anything about its dark matter content, or infer anything about the regions of the Galaxy that we can't survey from those which we can.

In recent years I have become more and more fascinated by the outer regions of the Milky Way's disc, where the stellar distribution is substantially disturbed. By studying this region of the Galaxy I believe that we can conduct 'Galactic seismology' and learn more about the structure of the Milky Way by studying how disturbances have propagated through it. 

Additionally I have dedicated significant work to interpreting simpler datasets in an effort to establish our current level of knowledge about the Milky Way. This includes my widely used gravitational potential models, from my highly cited papers "The mass distribution and gravitational potential of the Milky Way (2017) " , and "Mass models of the Milky Way (2011)" which attempt to distill our current understanding of the Galaxy's structure into a single model.

View my full publication list.

I am co-supervisor of three PhD students: 

Simon Alinder, who is investigating the disturbance of the Milky Way's outer disc, particularly the so-called 'phase spiral'.

Eero Vaher, who is investigating the stars that have escaped nearby open clusters, and the Gaia mission's accuracy for bright stars.

Isabella Henum, who is working as part of the MWGaiaDN MSCA Doctoral Network, quantifying the impact of GaiaNIR on our understanding of the Milky Way.

I was previously the co-supervisor of Daniel Mikkola who finished his PhD in 2022, having studied the influence of spiral arms, the velocity distribution of white dwarf stars, and of stars in the Milky Way's stellar halo.

I teach two units of the first year Mathematical Physics course (PA1720) and supervise literature review and project students. I also teach tutorials and am designing a new course in computational fluid dynamics.

Previously I was course leader and lecturer of the "Statistical methods in astrophysics" masters course, and coordinator of bachelors' thesis projects in astrophysics at Lund Observatory. For this work I won the Lund University Students' award for outstanding teaching contribution.

My work for the press and other media has included a press release related to my study of the ripples in the outer Milky Way, which attracted worldwide attention, including Forbes Science section and lead to me working with the Finnish popular astronomy magazine 'Tähdet ja avaruus' which produced a two-page spread on the results.

I have also worked with ESA's media department to create outreach material for Gaia's data releases, and with Anna Arnedottir to produce a planetarium show which contained the orbits of the Milky Way's globular clusters and dwarf galaxies.

I am available to talk about the Milky Way's evolution and structure and the Gaia mission.

Lund University students' award for outstanding teaching contribution (Lunds studenters pedagogiska pris för framstående insatser i utbildningen), January 2021

Swedish Research Council (Vetenskapsrådet) project grant "The disturbed Milky Way", 3,440,000 SEK, November 2021. 

Swedish Research Council (Vetenskapsrådet) project grant "Determining the gravitational field of the Milky Way with Gaia data", 3,440,000 SEK, October 2017. 

Walter Gyllenberg foundation grant from the Royal Physiographic Society of Lund, for computing resources and academic visitors, 260,000 SEK, December 2014.