GOVERNMENT

A massive computer simulation, led by a team of Ontario and US researchers using some of Canada’s top supercomputers to confirm that black holes have had a role in the evolution of galaxy, has won the 2007 ORION Discovery Award of Merit. The announcement was made at the annual ORION Awards, in Toronto, Ontario Monday, June 4, 2007. The research, which addressed one of the world’s computational Grand Challenges, required one of the world's largest computer-based simulations of its kind, spanning six billions years of cosmic history and 684 million light years of the universe. It involved high performance computing facilities at SHARCNET and HPCVL in Ontario and WestGrid in Alberta, interconnected over Canada’s advanced research networks. Over the last decade or so, high-precision surveys indicated that galaxies tend to evolve in a hierarchical way. Dwarf galaxies merge to form galaxies, galaxies merge to form galaxy clusters, and so on. The big anomaly was that large galaxies stop forming stars much sooner than smaller ones, which indicated that something was missing from the prevailing astrophysical model. A wide range of clues suggested that the role played by the enormous black holes that reside at the centres of galaxies was the missing factor. Remarkably, black holes release a significant amount of energy into their environs, because of the hot accretion disks that form around them, and it was thought that this could dramatically affect the evolution of the gas within a galaxy. To test this hypothesis, project lead Prof. Robert Thacker, adjunct faculty member in the Department of Physics, Engineering Physics and Astronomy at Queen's University in Kingston, partnered with Prof. Hugh Couchman, Scientific Director of SHARCNET, and Dr. Evan Scannapieco, of the Kavli Institute for Theoretical Physics, at the University of California, Santa Barbara, to conduct what was then the world's largest computer simulation of its kind. The 2006 simulation was able to confirm that black holes have a strong impact on the evolution of the largest galaxies in the universe, and that black holes in the largest galaxies and galaxy clusters emit enough energy to perturb the intra-cluster gas. The scientists made movies of the simulation remotely, which were particularly useful in understanding the impact of heating from black holes. The most important data are now archived at Queen's and still being analyzed. Prof. Thacker, who credits significant upgrades in connectivity between institutions thanks to ORION and CA*net 4 and other network infrastructure to the success of the research, notes that the massive simulation project could only go ahead once a high-speed connection over ORION and CAnet 4 was established between SHARCNET and WestGrid. The visualization was largely performed on the facilities at Simon Fraser University on the WestGrid visualization server. Prof. Thacker was recently named Canada Research Chair (CRC) in Astronomy and Astrophysics at Saint Mary’s University in Halifax, where he will develop new physical models and computational techniques to unravel the complex interplay between the formation and death of individual stars within the global evolution of a single galaxy. For more information, please visit its Web site.