Research Interests
Relativistic Astrophysics
Relativistic astrophysics is the application of the theory of
general relativity (the theory of strong gravitational fields)
to problems in astrophysics. The strongest gravitational fields
in the universe are associated with compact objects (neutron stars and
black holes).
The main focus is on providing a clearer understanding
of the electromagnetic and gravitational radiation produced by
compact objects. My research is theoretical and I use a mix
of analytical and numerical techniques.

Relativistic Effects in Accreting Neutron Stars and Black Holes:
The motivation
for some of my recent work has been the observation of
kHz quasiperiodic xray oscillations originating from accreting neutron stars
and black holes by NASA's
Rossi Xray Timing Explorer satellite.
I have been investigating
the possibility of detecting strongfield
relativistic effects such as the
precession of an accretion disk due to framedragging.

Neutron Star Oscillations and Instabilities:
I am also working on
studies of nonradial oscillations of rotating neutron stars,
including mechanisms for the production of gravitational
radiation. If a neutron star is rotating, gravitational
radiation can drive an instability which will cause the star to
slow down.
A great
surprise was a recent result that perturbations
driven by the Coriolis force can be unstable at arbitrarily small
angular velocities. Further work which included
the effect of viscosity showed the gravitational radiation driven
instability of the Coriolis modes is important for the class of neutron
stars which are born rapidly rotating (such as the
pulsar found in the supernova remnant N157B). My present work
involves an investigation of the damping effect of
weak turbulence on linear modes in young neutron stars. I am
using techniques first developed for the study of convection in
the sun in order to determine the maximum mode amplitudes allowed
by modemode couplings.
I have written some reviews of recent results
in
Matters of Gravity (the newsletter of the APS topical
group on gravity). You can read slightly revised versions of
these reviews through the links below.
Sharon Morsink