Christopher Thompson
Email: thompson@cita.utoronto.ca
Research Summary
[
High Energy Astrophysics
]
Chris Thompson carries out research on neutron stars, magnetars, gamma-ray
bursts, astrophysical plasmas, and supernova core collapse.
Research Projects:
(September 2002 - August 2003)
Non-thermal X-ray Spectra of Magnetars
Thompson and Maxim Lyutikov (McGill) carried out Monte Carlo simulations
of the X-ray spectrum of a magnetar with a twisted external magnetic field.
Such a configuration maintains a significant optical depth to
scattering at the cyclotron resonance of the current-carrying charges.
If the charges are mildly relativistic (as is expected in the gravitational
potential of a neutron star) then an input blackbody spectrum is modified
by multiple scattering, and aquires an extended high-energy power law tail.
Non-linear Relativistic Magnetofluids in Strong Gravitational Fields
Parker Troischt, a graduate student at UNC-Chapel Hill, performed a
series of calculations under the supervision of Thompson. He
demonstrated how the exact, non-linear wave solutions of force-free
magnetohydrodynamics are modified by a strong gravitational field.
Beyond the WKB limit, there is a non-linear coupling between torsional
and compressive waves. The effect of zero-frequency components of
the wave on the non-linear coupling between force-free waves was also
worked out, taking into account the finite compressibility of a
relativistic magnetofluid.
X-ray Outburst and Glitch Activity in an Anomalous X-ray Pulsar
Thompson collaborated with Kaspi (McGill) and Woods (MSFC) on the analysis
and interpretation of the recent X-ray activity of the Anomalous X-ray
Pulsar 1E 2259$+$586. This activity is strongly reminiscent of the
burst activity of SGRs, but on a smaller scale. The source also underwent
a large-amplitude glitch, probably triggered by the same instability that
produced the SGR-like bursts and enhanced X-ray emission. The large
magnitude of the glitch suggests that either it was localized in the core
of the neutron star; or that the superfluid rotation rate was below
that of the solid crust and magnetosphere. As Thompson had suggested
in earlier theoretical work, internal magnetic torques would have this
effect.
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