Superfluidity in neutron stars is a quantum state where matter flows without viscosity, often linked to glitches and cooling mechanisms.Neutron star superfluidity is a quantum phenomenon occurring in the interior of neutron stars, where matter flows without any viscosity. This state arises because neutrons, being fermions, can pair up at extremely high densities and low temperatures to form bosonic Cooper pairs, which then condense into a superfluid. This is analogous to superconductivity in metals, but with neutrons instead of electrons. The superfluid state is crucial for understanding several observed behaviors of neutron stars, particularly their cooling rates and the sudden spin-up events known as glitches.
The concept was proposed in the late 1960s by Arkady Migdal and others, who suggested that neutron stars might contain a superfluid phase. The link to glitches was developed in the 1970s by theorists like Pines and Anderson.
In a neutron star, the core is so dense that neutrons pair up via the strong force, forming a superfluid that can flow without resistance. When the star's rotation slows down over time, the superfluid's vortices (quantized whirlpools) can suddenly unpin from the crust and move outward, transferring angular momentum and causing a rapid spin-up — a glitch. This mechanism is similar to how vortices behave in laboratory superfluids, but on a cosmic scale. The superfluid also enhances neutrino emission, which accelerates the star's cooling.
Understanding neutron star superfluidity helps astrophysicists interpret pulsar timing data and constrain the equation of state of dense nuclear matter, which is relevant for nuclear physics and gravitational wave astronomy.
A neutron star superfluid can rotate with thousands of tiny vortices, each carrying a quantum of angular momentum, and their collective motion can cause the star to 'glitch' — a sudden change in rotation period observed in pulsars like the Crab.
