A picture of me.

Welcome to my website!

I am a professor at the University of British Columbia and a Canada Research Chair in Neutron Stars and Black Holes. My recent research has focussed on compact objects: white dwarfs, neutron stars and black holes. These are the most extreme objects in the universe since the Big Bang. Astrophysicists think that they provide the power behind quasars and gamma-ray bursts, the brightest objects in the recent universe.

If you would like to work with me, I encourage you to check out the Student/Postdoc page where you will find a list of potential, completed and in-progress projects. There are also links to the courses that I have taught.

If you wish to learn more about what I do, what I have written, what has been written about my work, what I have said or how to get a hold of me, I invite you to follow the links at the top of the page (or at the bottom for people with text-based browsers).

To put it concisely I study neutron stars and black holes from an astrophysical perspective. Because I am a theorist I focus what these objects can tell us about fundamental physics and how our current knowledge or speculation about fundamental physics can help us understand these phenomena. The areas of physics that my research sometimes covers include:

High-energy astrophysics Nuclear physics High-energy physics (particle physics) General relativity

Cosmology Condensed matter physics Atomic physics Classical dynamics

The bright dot in the image to the right is most likely a black hole or neutron star that was produced in a supernova seen about 320 years ago. The supernova itself is a bit mysterious as it was unusually faint. Most likely, the star that exploded had already expelled much of its outer layers before the explosion. Until the Chandra X-ray observatory pointed its mirror toward the supernova remnant Cassiopeia A, we did not know whether the supernova produced a black hole, a neutron star or left no remnant at all.

Soon after opening its protective shutter, the Chandra X-ray observatory took this picture of the supernova remnant Cassiopeia A.

Understanding how a neutron star appears to our telescopes on and near Earth is an important part of my recent research. Observations of neutron stars can tell us about the nature of matter at extremely high densities, about the forces that hold nuclei together and about how materials and the vacuum itself are distorted by intense gravitational and magnetic fields.

Neutron stars reveal themselves in several different ways. As a massive star runs out of fuel, its inner regions collapse to form a very hot neutron star. This collapse drives the explosion of the rest of the star -- a supernova. The neutron star remains hot enough to been seen by X-ray telescopes orbiting the Earth for ten thousand to one million years like in the image. This cooling radiation and how it changes will time give important hints on the composition of the inside of neutron stars.

Many stars have one or more companions. If one of the stars explodes as a supernova and leaves a neutron star as a remnant, the neutron star can accrete material from the companion. This matter heats up as it falls toward the neutron star and hits its surface. This hot material emits X-rays which we also observe from X-ray telescopes. This radiation also gives important clues about the nature of neutron stars and their environment.