Model-Independent Determination of the Tidal Deformability of a 1.4 $M_{\odot}$ Neutron Star from Gravitational-Wave Measurements

TL;DR

This paper introduces a data-driven, model-independent method to determine the tidal deformability of a 1.4 solar mass neutron star from gravitational-wave data, providing EOS-agnostic constraints that improve with future observations.

Contribution

It presents a novel approach to constrain neutron star tidal deformability directly from GW data without relying on specific EOS models, enhancing robustness and applicability.

Findings

EOS-independent constraint of Λ₁.₄ = 222.89_{-98.85}^{+420.33}

Multimessenger limit of Λ₁.₄ = 265.18_{-104.38}^{+237.88}

Higher-order terms have negligible impact under current uncertainties

Abstract

Tidal deformability of a 1.4 $M_\odot$ neutron star provides a pivotal window into the physics of dense nuclear matter, bridging gravitational-wave(GW), electromagnetic observations and nuclear physics. In this work, we present a novel, data-driven approach to constrain $\Lambda_{1.4}$ without invoking specific equation-of-state(EOS) models. By interpolating directly over the mass--tidal-deformability posteriors from GW170817, we obtain an EOS-independent constraint of $ \Lambda_{1.4} \;=\; 222.89_{-98.85}^{+420.33}. $ We further combine these GW-based results with the X-ray EOS-independent constraint from \cite{Huang_2025}, deriving a multimessenger limit of $ \Lambda_{1.4} \;=\; 265.18_{-104.38}^{+237.88}, $ which remains largely EOS agnostic. This framework demonstrates that higher-order terms neglected in linear expansion methods do not significantly affect $\Lambda_{1.4}$ estimates under current observational uncertainties. As gravitational-wave detectors improve in sensitivity and more binary neutron-star mergers are discovered, our purely data-driven strategy can serve as a robust standard baseline for extracting neutron-star interior properties without relying on unverified EOS models.