Dr Vanessa Graber (Royal Holloway University of London) gives a webinar on ‘Simulating sudden hiccups of superfluid neutron stars in 3D’ at 4pm UK time.

Chair: Samuli Autti (Lancaster University)

Formed in the core-collapse supernovae of massive stars, neutron stars are compact remnants that unite many extremes of physics. In particular, in terms of their high densities, neutron stars are sufficiently cold to contain macroscopic quantum condensates. The key observational signature for this cosmic superfluidity is pulsar glitches, sudden spin-ups that occasionally interrupt the otherwise regular spin-down of neutron stars. The stellar dynamics after a glitch involves the transfer of angular momentum between different neutron star layers through various physical processes, including Ekman pumping, superfluid vortex-mediated mutual friction, and magnetic fields. Observing these hiccups, thus, provides a unique window into the neutron star interior hidden from direct view. However, experimental and numerical validations of analytical predictions based on simplified models have been limited. In this talk, I will present our recent work on nonlinear hydrodynamical simulations of the spin-up problem in a two-component fluid in the presence of viscous effects and mutual friction. By solving the incompressible HVBK equations in the full sphere for a range of Ekman numbers and mutual friction strengths, we are able to study the post-glitch behaviour across the entire interior for the first time. I will summarise the main results of our study and discuss potential implications for neutron stars.