Home Page

Credit: Wheeler Studios

About Me

I studied Physics and Astronomy at the University of British Columbia through 1981, and then went on to do a PhD at Leiden University with a thesis entitled “The Interaction of Supernovae with the Interstellar Medium”. After obtaining my PhD in 1985, I filled the role of research associate and then assistant scientist at the Very Large Array of the National Radio Astronomy Observatory (1985 – 1989). I subsequently filled a series of roles at ASTRON, the Netherlands Institute for Radio Astronomy (1989 – 2007), beginning with leading the Telescope Observing Group (1989 – 1992), then as staff astronomer (1992 – 2003) and finally as head of the ASTRON scientific staff (2004 – 2007). I led the Astrophysics Theme and Research Program of CSIRO Astronomy and Space Science (CASS) from 2007 – 2011 and then the role of Chief Scientist for CASS through 2013. In 2011 I was named an Honorary Professor of the University of Sydney. From June 2013 I’ve taken on the role of Square Kilometre Array Science Director based at the SKA Headquarters south of Manchester, UK.

My astrophysics research has focused on the interstellar and intergalactic medium of our own, nearby and distant galaxies. A primary tool in this endeavour has been the 21cm line of neutral hydrogen (HI), but insight into the evolving star formation rate in galactic disks has also come from the radio continuum and infrared portions of the electromagnetic spectrum. Recent contributions have included elucidation of the interaction history (over the past 5 billion years) of one of the nearest external galaxies, Messier 31, via extremely sensitive HI imaging of its extended environment. Faint gaseous filaments, which likely have only a microscopic neutral fraction, trace the ancient interaction of Messier 31 and it’s smaller companion, Messier 33. The debris of that interaction fuels ongoing accretion onto both systems. Similar phenomena, dating from an earlier epoch of enhanced interaction, are likely the reason that a statistical excess of neutral hydrogen is found in the environment of many galaxies. This has been pursued in a recent PhD project under my supervision to detect and study comparable systems for a wide range of host galaxy masses and environmental conditions. Another research focus of the past years has been the detection and documentation of the large-scale magnetic field topology of nearby galaxy disks, a vital constituent of the cosmos that is only beginning to reveal its prevalence and importance.

I’ve also enjoyed involvement in astronomy instrumentation projects throughout this period, with early contributions to the Atacama Large Millimetre Array (ALMA), a $2b international facility now approaching completion in Chile, in the areas of configuration design and wide-field imaging techniques. I also contributed to the design of the European Southern Observatory (ESO) Very Large Telescope (VLT), an array of four 8.2 metre diameter telescopes (construction cost of about $1b) located in northern Chile that define the current state-of-the-art in optical astronomy. As member of the ESO VLT Interferometry panel I determined the optimal arrangement of the telescopes for combined use as an interferometer and my design was adopted for construction. Perhaps the most fundamental contribution in this area was development of the original concept and science case for the Square Kilometre Array (SKA). I made the proposal to the International Union of Radio Science (URSI) that a working group be initiated to explore the prospects for such a next generation radio facility and served as convenor of the resulting “URSI Large Telescope Working Group” (1993 – 1999). In this capacity, I organised and chaired a series of scientific and technical workshops at six monthly intervals throughout North America, Europe and Australasia. The outcome of this effort was establishment of the international SKA project (likely budget of $3b) and the first written science case for the project.