I was born in Australia and I have been in North America (primarily Canada) since 1992, when I started Graduate work in Astronomy at the University of Toronto. Working with my supervisor Dick Bond at CITA I applied gasdynamical simulations to the Lyman alpha forest problem. I was a postdoc at the University of Washington working with Craig Hogan and the "N-body Shop" group where I wrote the Gasoline code with Joachim Stadel and Tom Quinn. I then came to McMaster to work with Ralph Pudtriz and Hugh Couchman in Physics and Astronomy. In 2002 I switched from full-time research to start spending time all over campus assisting researchers to develop parallel programs for the new SHARCNET supercomputer clusters. I was still involved in cutting edge astrophysics research and in July 2003 I took up a tenure track position with the Physics and Astromomy Department at McMaster.

Computational Astrophysics: Cosmology, Galaxy Formation, Star Formation, Protoplanetary Disks, Hydrodynamics, Numerical Methods, Parallel Computing

James Wadsley
Department of Physics & Astronomy
McMaster University

Dear Prospective Graduate Student,

Computational astrophysics enables the astronomer's dream of seeing stars and galaxies come to life and evolve before their eyes. Young stars can have substantial amounts of gas in disks around them. With computer simulations we have demonstrated that these disks spontaneously fragment under ideal conditions to create giant gas planets larger than Jupiter. We can also help the process by smashing disks together, shredding them into a string of brown dwarfs. We are also modeling entire clusters of young stars for a much more realistic and violent star and planet forming environment.  Gas fragments when it cools and radiation is how heat is lost.  We have developed numerical radiative transfer models to follow infrared radiation that dominates heating and cooling within dusty disks and star forming regions as well as UV radiation coming from massive stars and black hole accretion disks.

A major success of our recent cosmological simulations is the formation of realistic spiral galaxies on a supercomputer. The simulated disk galaxies form over billions of years, consuming gas and smaller galaxies in what is regarded as fairly quiet evolution and look remarkably like the Milky Way. With the resolution we can achieve on supercomputers, we have shown that small galaxies are sufficiently violent to gravitationally eject dark matter from their cores -- solving a key mystery in cold dark matter. Dramatic merger events can transform quiet galaxies into the full range of galaxies types seen in the universe and also drive some of their gas and stars into voracious black holes at their centres. To model these galaxies even better we are developing detailed prescriptions for the gas and how it cools, black holes, how stars form and how stars die in energetic supernova explosions.  A key new development is the importance of clustered supernovae: hundreds going off in a small region.

My work involves computer simulations of astrophysical systems including gravity, gas, radiation and other physics. We have used the parallel Gasoline code to simulate planets, brown dwarfs, young stars, supermassive black holes, galaxies, galaxy clusters and large scale structure in the universe. Some recent papers are listed at NASA ADS. Images and movies can be seen at https://www.physics.mcmaster.ca/~wadsley/research. McMaster Physics and Astronomy now has a large group of working in computational astrophysics including five faculty, several graduate and undergraduate students and postdocs. We use powerful SHARCNET and Compute Canada parallel supercomputers to get the job done. 

I currently have graduate students working on cosmological galaxy formation, protostellar disks, star formation and numerical methods. I like to have a hands-on, collaborative working relationship with students where we jointly contribute to projects. My students can be involved in picking the astrophysical questions to ask, astrophysical theory, developing parallel code, trying out new physical models in simulations, designing and running astrophysical simulations and/or matching results to astronomical observations according to their preferences and how they like to work with others in the group. Students also write papers and present results at conferences in Canada and internationally. I have collaborators in Zurich and Seattle and there are prospects for joint projects and exchanges with those universities. I have co-supervised several students and I am open to joint thesis projects with other faculty in the department. I also usually take on one or two summer, co-op or undergraduate thesis students every year.

I am interested in applications for graduate work at the M.Sc. or Ph.D. level in the areas listed above. I particularly encourage applications from students with both physics and programming skills.

I encourage you to email me: wadsley@mcmaster.ca or arrange to visit McMaster in person.

Regards,
James Wadsley