Steven A. Balbus
University of Oxford
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Primary Section: 12, Astronomy Secondary Section: 13, Physics Membership Type:
Member
(elected 2015)
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Biosketch
Steven Balbus is an astrophysicist known for his studies in astrophysical fluid dynamics. He is perhaps best known for his work with J. Hawley on what is now usually referred to as the magnetorotational instability, a highly destabilizing process believed to be at the heart of accretion disk turbulence, for which Balbus and Hawley were awarded the Shaw Prize in Astronomy in 2013. Balbus is a native of Philadelphia, PA. He took undergraduate degrees in mathematics and physics at the Massachusetts Institute of Technology, and completed a PhD in theoretical astrophysics at UC Berkeley in 1981. After postdoctoral positions at MIT and Princeton, Balbus joined the faculty of the University of Virginia in 1985. He moved to the Ecole Normale Supérieure in Paris in 2004, where he was Professor of Physics, Classe exceptionnelle and was awarded a Chaire d’excellence for his research on accretion disks. In 2012, he moved to Oxford University as the Savilian Professor of Astronomy and a Professorial Fellow of New College. He is currently the Head of the Astrophysics Sub-Department at Oxford.
Research Interests
Steven Balbus’s research interests span a broad range of topics in theoretical astrophysics. Early work included investigations of heating and cooling processes in the interstellar medium and gasdynamical processes in spiral galaxies. Since the early 1990’s Balbus has been studying turbulence in accretion disks in many different astrophysical environments. How the Keplerian gas flow in such disks degenerates into turbulence, as observations strongly imply, had been a major problem in astrophysics. In a series of papers starting in 1991, Balbus and J. Hawley showed that the presence of any weak magnetic field in a rotating gas leads to a rapid instability, if the rotation rate of the gas decreases radially outwards. This is a much less stringent requirement than the classical Rayleigh criterion that the specific angular momentum decrease outwards. Subsequent computer simulations revealed the transition from laminar to turbulent flow, and the field of numerical accretion disk studies began. Balbus developed these ideas further, showing how weak magnetic fields profoundly affect the stability of dilute plasmas yet more generally. He has made important contributions to the theory of the Sun’s internal rotation, and has recently ventured into a very different field: how palaeozoic ocean tides may have influenced vertebrate evolution.
