Friction in superfluids : the curious case of neutron stars
The defining property of superfluids is their ability to flow without friction. However, the presence of quantized vortices can open new dissipative channels that lead to hydrodynamic friction. Understanding this mechanism is a fundamental ingredient to model neutron star phenomenology, like pulsar glitches, oscillation modes damping, and cooling in old pulsars. Recent simulations of vortex motion in a disordered environment allowed to test some qualitative features expected for this kind of friction : the main results and their relevance for the astrophysical phenomenon of pulsar glitches will be discussed.