Inferring neutron star properties from GW170817 with universal relations

Bharat Kumar; Philippe Landry

doi:10.1103/PhysRevD.99.123026

paper

Inferring neutron star properties from GW170817 with universal relations

arXiv:1902.04557 · doi:10.1103/PhysRevD.99.123026

Abstract

Because all neutron stars share a common equation of state, tidal deformability constraints from the compact binary coalescence GW170817 have implications for the properties of neutron stars in other systems. Using equation-of-state insensitive relations between macroscopic observables like moment of inertia ( $I$ ), tidal deformability ( $Λ$ ) and stellar compactness, we derive constraints on these properties as a function of neutron-star mass based on the LIGO-Virgo collaboration's canonical deformability measurement, $Λ_{1.4} = 19 0_{- 120}^{+ 390}$ . Specific estimates of $Λ$ , $I$ , dimensionless spin $χ$ , and stellar radius $R$ for a few systems targeted by radio or X-ray studies are extracted from the general constraints. We also infer the canonical neutron-star radius as $R_{1.4} = 10. 9_{- 1.5}^{+ 1.9}$ km at 90 $%$ confidence. We further demonstrate how a gravitational-wave measurement of $Λ_{1.4}$ can be combined with independent measurements of neutron-star radii to tighten constraints on the tidal deformability as a proxy for the equation of state. We find that GW170817 and existing observations of six thermonuclear bursters in low-mass X-ray binaries jointly imply $Λ_{1.4} = 19 6_{- 63}^{+ 92}$ at the 90 $%$ confidence level.

18 pages, 7 figures; corrected multimessenger tidal deformability constraint

Inferring neutron star properties from GW170817 with universal relations

Abstract

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