THE SHORT VERSION is that I'm interested in the physics of accretion phenomena, the formation and evolution of planetary systems, and the astrophysics of black holes.
Simulation of black hole accretion
Much of my work focuses on understanding:
Protoplanetary disks
Unraveling the environment within which planet formation occurs requires modeling the coupling
between magnetic fields, self-gravity and dust physics within protoplanetary disks. I am currently
working with APS graduate student Anna Hughes on the evolution of dust within evolving disks, and
with Barbara Ercolano to develop time-dependent models for X-ray ionized disks. At a more first
principles level, my group is taking a new look at how angular momentum transport occurs in
poorly ionized disks in which non-ideal MHD effects are dominant.
Formation and evolution of planetary systems
Extrasolar planetary systems appear very different from the Solar System: some have gas
giants with orbits far interior to that of Mercury, while others display highly eccentric or
inclined orbits. I have been working - most recently with Sean Raymond and Richard Alexander -
to determine how these properties of the population can be understood. Our work suggests that the Solar System, and extrasolar planetary
systems, may be limiting cases of a single dynamical model that includes both planet-planet
scattering and planet-disk interactions. We are now studying possible implications for habitable
planet formation.
Accretion disk physics
In work led by Ken Rice, Richard Alexander and
Giuseppe Lodato, we have completed detailed studies of the outcome of gravitational
instability in disks around both young stars and massive black holes. With Kris
Beckwith I am currently working on a problem that has long interested me - how
important are global effects on the evolution of magnetic instabilies in accretion disks?
Ultimately, we hope to connect theory to observed phenomena in X-ray binaries.
Black hole mergers
It is widely thought that the merger of galaxies is followed by the coalescence of
their nuclear black holes, but the mechanisms and observable consequences of such
mergers remain unknown. With Elena Rossi, Jorge Cuadra, and colleagues, I am working
on the role of gas in driving mergers, and on making predictions for electromagnetic
counterparts to coalescences detected via gravitational wave emission.
Favorite papers
The work that I'm most pleased with...
Turbulence and angular momentum transport in a global accretion disk simulation - what it says on the box, done before it was fashionable
Accretion during the merger of supermassive black holes - how gas disks respond to mergers
Investigating fragmentation conditions in self-gravitating accretion discs - an answer to the question of when disks fragment
Planet-planet scattering in planetesimal disks... - a unified model for Solar and extrasolar planetary system evolution