Bridging the gap by shaking superfluid matter

TL;DR

This paper demonstrates that large amplitude density oscillations in cold compact stars can significantly enhance weak Urca reactions, overcoming superfluid suppression and affecting neutrino emission and viscosity.

Contribution

It reveals how density oscillations can bridge the suppression gap caused by superfluidity, impacting transport properties in dense stellar matter.

Findings

Weak Urca reactions are strongly enhanced during large amplitude oscillations.

Neutrino emissivity and bulk viscosity are significantly affected by pairing patterns.

Superfluid suppression can be overcome by oscillation-induced effects.

Abstract

In cold compact stars, Cooper pairing between fermions in dense matter leads to the formation of a gap in their excitation spectrum and typically exponentially suppresses transport properties. However, we show here that weak Urca reactions become strongly enhanced and approach their ungapped level when the star undergoes density oscillations of sufficiently large amplitude. We study both the neutrino emissivity and the bulk viscosity due to direct Urca processes in hadronic, hyperonic and quark matter and discuss different superfluid and superconducting pairing patterns.