Mountain building of solid quark stars

TL;DR

This paper explores the potential for mountain formation on solid quark stars, estimating their maximum mountain heights and gravitational wave emissions, which could help distinguish them from neutron stars.

Contribution

It provides the first estimation of maximum mountain heights and gravitational wave signals for solid quark stars, considering realistic breaking strains and mass constraints.

Findings

Maximum mountain height on solid quark stars can be significant, up to 'potato-like' shapes for very low masses.

Gravitational wave amplitude from solid quark stars is estimated to be around 10^{-27}.

Solid quark stars could have distinct gravitational wave signatures compared to neutron stars.

Abstract

One of the key differences between normal neutron and (bare) quark stars is relevant to the fact that the former are gravitationally bound while the latter self-confined unless their masses approach the maximum mass. This difference results in the possibility that quark stars could be very low massive whereas neutron stars cannot. Mountains could also be build on quark stars if realistic cold quark matter is in a solid state, and an alternative estimation of the mountain building is present. As spinning compact objects with non-axisymmetric mass distribution will radiate gravitational waves, the equations of states of pulsars could be constraint by the amplitude of gravitational waves being dependent on the heights of mountains. We then estimate the maximum mountains and thus quadrupole moment on solid quark stars, to be consistent with that by Owen (2005) if the breaking strain is 0.1, addressing that a solid quark star with mass < 10^{-2} Msun could be `potato-like'. We estimate the gravitational wave amplitude of solid quark stars with realistic mountains to be order of h0 ~ 10^{-27}.