Astrophysics Colloquium - Neutron star hiccups as probes for ultra-dense matter

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 signatures for this cosmic superfluidity are pulsar glitches, sudden spin-ups that occasionally interrupt the otherwise regular spin-down of neutron stars. Stellar dynamics after a glitch involve the transfer of angular momentum between different neutron star layers through various physical processes. Observing these hiccups, thus, provides a unique window into the neutron star interior hidden from direct view. In this talk, I will introduce the physics across vastly different length scales that affect the glitch dynamics and discuss how observations of this phenomenon can help us constrain the properties of ultra-dense matter. I will specifically highlight the role that advanced machine learning techniques, such as simulation-based inference, and future observations with the SKA will play in this endeavour.