Cavitation from bulk viscosity in neutron stars and quark stars

TL;DR

This paper explores how high bulk viscosity in quark matter can cause cavitation-like fragmentation in neutron and quark stars, impacting their stability, oscillations, and gravitational wave signals.

Contribution

It introduces the concept of cavitation due to bulk viscosity in dense stellar matter, linking it to observable astrophysical phenomena and questioning hydrodynamical models.

Findings

Bulk viscosity can induce mechanical instability in quark matter.

Cavitation may lead to star fragmentation and phase transitions.

Implications for gravitational wave signals and strangelet formation.

Abstract

The bulk viscosity in quark matter is sufficiently high to reduce the effective pressure below the corresponding vapor pressure during density perturbations in neutron stars and strange stars. This leads to mechanical instability where the quark matter breaks apart into fragments comparable to cavitation scenarios discussed for ultra-relativistic heavy-ion collisions. Similar phenomena may take place in kaon-condensed stellar cores. Possible applications to compact star phenomenology include a new mechanism for damping oscillations and instabilities, triggering of phase transitions, changes in gravitational wave signatures of binary star inspiral, and astrophysical formation of strangelets. At a more fundamental level it points to the possible inadequacy of a hydrodynamical treatment of these processes in compact stars.