Speaker
Description
Neutron stars are the collapsed cores of massive stars that have undergone a supernova explosion. They are the densest known astrophysical objects, with a mass typically 1.4 times that of the Sun compressed into a radius of approximately 10 km. Deep within the star, where the density exceeds the nuclear equilibrium density, neutrons become superfluid and protons become superconducting. As a result, the star’s rotation and magnetic flux become are quantised into extremely thin vortices and fluxtubes respectively. These vortices pin to nuclear lattice sites or defects in the star’s crust. When the star’s rotation rate slows down, the vortices move outward to conserve angular momentum. At the same time, these vortices unpin and self-reorganise to release the stored angular momentum in catastrophic discrete events known as rotational glitches which are observed as an instantaneous increase in the observed rotation rate of pulsars. A complete theory of the micro and macroscale superfluid dynamics to explain this phenomenon does not yet exist and current theoretical models are hampered by an incomplete understanding of the interactions between superfluid vortices, fluxtubes and crustal nuclei. In my talk, I would like to focus on the latest results of modelling vortex avalanches using mesoscopic models of superfluidity, namely the point vortex model and the vortex filament model. In particular, I will show the latest results of our attempts to simulate vortex avalanches using a relatively large vortex lattice in the vortex filament model, which is a regime that has not been fully explored before.