Magnetic oscillations of a neutron star crust and interior following a glitch
Nordita Astrophysics seminars
Wednesday 05 February 2014
to 14:30 at
C. Anthony van Eysden (Nordita)
Following a glitch, the crust and magnetised plasma in the outer core of a
neutron star are believed to rapidly establish a state of co-rotation
within a few seconds by process analogous to classical Ekman pumping.
However, in ideal magnetohydrodynamics, a final state of corotation is
inconsistent with conservation of energy of the system.
We demonstrate that, after the Ekman-like spin up is completed,
magneto-inertial waves continue to propagate throughout the star, exciting
torsional oscillations in the crust and plasma.
The crust oscillation is irregular and quasi-periodic, with a dominant
frequency of the order of seconds.
Crust oscillations commence after an Alfven crossing time, which is
approximately two and a half minutes at the magnetic pole, and are
subsequently damped over the much longer viscous diffusion time, ranging
from days to months depending on the temperature of the star.
Because of their short periods, it is unlikely that the oscillations
correspond to any observed phenomena in radio timing data.