About me

Welcome! I am a postdoctoral fellow at the Canadian Institute for Theoretical Astrophysics (CITA). As a theoretical astrophysicist with a background in applied mathematics and fluid dynamics, I use analytical and computational tools to tackle a wide variety of problems.

My research program revolves around the dynamics of rapidly rotating astrophysical flows. I study astrophysical systems ranging from magnetized accretion flows around black holes, to our own Jupiter and Saturn, to rapidly spinning and tidally interacting stars.

Seismology

Seismology provides an important window into the deep internal structures of stars and planets. The deep interiors of stars and planets remain mysterious even in our own solar system. My research in seismology focuses on how rotation affects the global-scale vibrations ("normal mode" oscillations) of planets and stars.

The centrifugal effects of rotation modify the internal structures of planets and stars, by flattening objects that would otherwise be spherical. This animation shows progressively stronger centrifugal flattening of a star with increasingly rapid rotation:

Together with the Coriolis force, these changes in internal structure also modify stellar and planetary vibrations.

Saturn ring seismology

Saturn and Jupiter spin very rapidly, at 40% and 30% of the rates at which they would fly apart. This makes them exciting testbeds for how rotation affects planets' structures and dynamics.

Fortuitously, Saturn's rings also act as an effective seismograph: some of Saturn's oscillations apply torques that drive waves in the planet's rings. Observations of these waves by the Cassini satellite have given us precise measurements of Saturn's natural vibrations, and by proxy its intrinsic properties.

I performed the first calculations of Saturn's oscillation modes to completely account for the planet's rapid bulk rotation, realistic internal structure, and deep surface winds. My work in Saturn ring seismology laid theoretical groundwork that my collaborators and I used to infer Saturn's deep spin rate and differential rotation profile.

Tidal interactions

Just as the moon raises tides in Earth's oceans, mutual gravity produces tidal bulges in stars, planets, and compact objects that orbit closely to one another. This animation shows a tidal bulge raised in a rotating gaseous planet by the gravitational pull of an orbiting satellite:

I characterized the properties of tidal bulges raised in planets and stars that are also centrifugally flattened by rotation. Additionally, I quantified the effect that tidal driving of internal waves can have on the shape of the bulge raised in Jupiter by its moon Io, and provided a theoretical comparison for similar measurements in Saturn. This cutout shows the types of internal waves that Io may be driving in Jupiter:

My ongoing work in tides focuses on the influences that the tidal dissipation of energy can have on orbital motion over time. I am particularly interested in tidal flows driven in systems with non-negligible orbital eccentricities and spin-orbit misalignments. This animation shows the highly dynamic tides raised in a star by a secondary mass with an eccentric (elliptical) orbit:

Accretion disks

Accretion disks facilitate planet formation, fuel the growth of stars and compact objects, and power some of the most energetic emission observed. My research in accretion disks focuses on waves and turbulence in magnetohydrodynamic (MHD) accretion disks that are distorted, with streamlines that are eccentric, warped, or otherwise non-circular.

Magnetized, eccentric disks

My current work in accretion disks focuses on the ways that eccentric disk distortions can interact with and affect magnetic fields. This video shows the precession of a 2D model of a steady state disk that is both strongly eccentric and threaded by a vertical magnetic field:

Variability in X-ray binaries

During my PhD, I studied wave excitation and propagation in accretion flows around black holes. I characterized a family of MHD waves the right frequencies to explain rapid variability that is occasionally observed in X-ray emitting binary systems. This variability is linked to the nature of accreting black holes.

This video shows vertical cross-sections through a cylindrical disk, and illustrates the excitation of radially trapped waves in a hydrodynamic black hole accretion flow. These waves are excited by a background eccentric distortion (which has been filtered out of the video with an average in the angular direction).

I showed that such wave excitation can also take place in magnetized accretion disks that are affected by MHD turbulence.

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