Gravitational waves from color-magnetic `mountains' in neutron stars

TL;DR

This paper proposes that color-magnetic vortices in neutron star cores could create non-axisymmetric deformations, producing gravitational waves detectable by future observatories, thus providing insights into quark matter in neutron stars.

Contribution

It introduces the concept that color-magnetic vortices in neutron stars can generate observable gravitational waves, linking quark matter properties to astrophysical signals.

Findings

Color-magnetic vortices induce non-axisymmetry in neutron stars.

Gravitational waves from these 'mountains' could be detected by the Einstein Telescope.

Detection is possible with magnetic fields ten times stronger than surface fields.

Abstract

Neutron stars may harbour the true ground state of matter in the form of strange quark matter. If present, this type of matter is expected to be a color superconductor, a consequence of quark pairing with respect to the color/flavor degrees of freedom. The stellar magnetic field threading the quark core becomes a color-magnetic admixture and, in the event that superconductivity is of type II, leads to the formation of color-magnetic vortices. In this Letter we show that the volume-averaged color-magnetic vortex tension force should naturally lead to a significant degree of non-axisymmetry in systems like radio pulsars. We show that gravitational radiation from such color-magnetic `mountains' in young pulsars like the Crab and Vela could be observable by the future Einstein Telescope, thus becoming a probe of paired quark matter in neutron stars. The detectability threshold can be pushed up toward the sensitivity level of Advanced LIGO if we invoke an interior magnetic field about a factor ten stronger than the surface polar field.