The Hidden Wind of Neutron Stars: How Neutrons Propel Magnetic Vortices ✛ ✎ ✦
The interiors of neutron stars are a realm of degenerate matter. Here, protons condense into a superconducting condensate, threaded by quantum vortices. Imagine tiny magnetic tops: each carries a quantum of magnetic flux and glides through the electron fluid. For a long time, astrophysicists saw them as surfers riding the crest of the "electron surf." But new research reveals: these surfers also have a tailwind — the neutron wind.
Previously, everything was explained by electron scattering on the vortex's magnetic field. This provided two forces at once: longitudinal and transverse, the Magnus force. But neutrons, as the normal component of the plasma, are not idle either. Through the Fermi liquid mechanism, they interact with protons. Drawing on the theory of Landau and BCS superconductivity (Bardeen–Cooper–Schrieffer), with the addition of quantum thermodynamics, the authors derived an additional force. It turned out to be purely longitudinal — directed strictly along the vortex motion and proportional to the velocity difference between neutrons and the vortex. If neutron-proton pairing is switched off, the force disappears — just as the wind dies when the air stills.
This "neutron thrust" rewrites the rules for magnetars and accreting neutron stars. It shows how the velocity difference between electrons and neutrons can be self-sustaining, without external influences. And this directly affects the evolution of magnetic fields and the damping of stellar oscillations. In prospect — a key to the mystery of anomalously rapid cooling of some stars and to the nature of pulsar glitches.
Ahead lies the abandonment of simplified vortex geometry. We will need numerical simulations with realistic equations of state and inclusion of superfluid neutrons. We have only just begun to probe the hidden currents in the ocean of superdense matter. And here's something to ponder: this microscopic force, born of the collective dance of particles, can steer the destiny of an entire star — a reminder that in extreme physics, nothing exists in isolation.
A cube of neutron star material weighs as much as Everest, and the magnetic fields in its vortices are billions of times stronger than anything we can create on Earth.