Speaker
Description
Neutron star cores could host various novel phases, ranging from a nucleonic superfluid phase to exotic high-baryon-density quantum chromodynamics (QCD) phases. Several observational signals have been discussed in the literature for such phase transitions. The current work points to a unique phenomenon, the Kibble–Zurek mechanism, in which a superfluid vortex network forms during a phase transition to a superfluid phase, such as the nucleon superfluid or a phase like the color-flavor-locked phase. The random vortex network is transient and leaves behind the primary vortices that arise from the star's initial angular momentum. However, the transient, random vortex network can have a non-zero net angular momentum, which can be oriented in an arbitrary direction. Due to the conservation of angular momentum, the normal component gains an equal and opposite angular momentum, thereby imparting the arbitrarily oriented angular momentum to the rest of the neutron star. For pulsars, the induced angular momentum would alter the pulse timing and profile, and the associated modulation will decay systematically as the vortex network decay, following characteristic scaling behaviour that could serve as a universal indicator of superfluid transitions in the neutron-star core.