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.
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.
Talks and posters
Here are a few talks and posters that I have presented both at conferences and publicly.