The Shaw Prize in Astronomy for 2013 is awarded to Steven A Balbus, Savilian Professor of Astronomy, University of Oxford, UK and John F Hawley, Associate Dean for the Sciences and VITA Professor and Chair of Department of Astronomy, University of Virginia, USA for their discovery and study of the magnetorotational instability, and for demonstrating that this instability leads to turbulence and is a viable mechanism for angular momentum transport in astrophysical accretion disks.
Accretion is a widespread phenomenon in astrophysics. It plays a key role in star formation, mass transfer in stellar binaries, and the growth of supermassive black holes in the centres of galaxies. Sources powered by accretion can even outshine those of similar mass powered by nuclear fusion.
Accreting matter typically carries angular momentum which causes it to flatten into a disk that orbits the central body. It was recognized long ago that disk accretion requires a mechanism for the outward transfer of angular momentum. Moreover, astronomical observations had established that many accretion powered sources are surrounded by disks. However, for many years the mechanism enabling the outward transfer of angular momentum remained elusive. All this was changed by Balbus and Hawley. Their discovery and elucidation of the magnetorotational instability (MRI) provides what to this day remains the only viable mechanism for the outward transfer of angular momentum in accretion disks.
Astronomy Selection Committee
The Shaw Prize
28 May 2013 Hong Kong