Superfluid neutron star dynamics, mutual friction and turbulence

Sidery, Trevor Lloyd (2008) Superfluid neutron star dynamics, mutual friction and turbulence. University of Southampton, School of Mathematics, Doctoral Thesis , 181pp.


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This thesis investigates the role of superfluidity in neutron stars and associated phenomena. We model the internal fluid of a neutron star as a two-component system: one of charged particles and one of superfluid neutrons. We derive a set
of multi-constituent hydrodynamic equations that allows for a mutual friction between the constituents. We show that when a velocity difference exists between the two constituents the momentum of each constituent is modified by an entrainment
parameter. Throughout all of this work we take direction from both theoretical and experimental work on superfluid Helium. This suggests that a force due to vortex lines in the superfluid acts between the two constituents. The hydrodynamic
equations are on a scale at which the effect of vortices can be averaged over. The form of the mutual friction between the two constituents depends on the configuration of the vortices. Firstly, we concentrate on an array of vortices. The mutual friction is calculated both for a straight array, and then extended to a ‘moderately’ curved array. We also investigate a turbulent model for the superfluid neutrons in which the vortices are in a tangle. To include rotation in our model we use a phenomenological approach to construct the mutual friction for a polarised tangle. The hydrodynamic equations are used to investigate how entrainment and mutual friction affect plane waves. We show that there are conditions in which the
waves are unstable and discuss how this may lead to turbulence. As a first step in considering the neutron star crust we consider how oscillations in the fluid are dissipated on a boundary. As before, we concentrate on the effects of entrainment and mutual friction. Finally, we consider a simple global model of the glitch phenomenon seen in neutron stars in which the important process is a reconfiguration of the vortex array. We use this model to consider how the observational data may constrain parameters.

Item Type: Thesis (Doctoral)
Subjects: Q Science > QB Astronomy
Q Science > QA Mathematics
Q Science > QC Physics
Divisions : University Structure - Pre August 2011 > School of Mathematics > Applied Mathematics
ePrint ID: 66270
Accepted Date and Publication Date:
March 2008Made publicly available
Date Deposited: 27 May 2009
Last Modified: 27 Mar 2014 18:47

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