2025ApJ...988L..75M

Gravitational-wave astronomy shows great promise in determining nuclear physics in a regime not accessible to terrestrial experiments. We introduce physics-informed priors constrained by nuclear theory and perturbative quantum chromodynamics calculations, as well as astrophysical measurements of neutron-star masses and radii. When these priors are used in gravitational-wave astrophysical inference, we show a significant improvement on nuclear-matter constraints. Applying these to the first observed gravitational-wave binary neutron-star merger GW170817, the constraints on the radius of a 1.4 M_⊙ neutron star improve from ${R}_{1.4}=12.5{4}_{-1.54}^{+1.05}$ to ${R}_{1.4}=12.1{1}_{-1.11}^{+0.91}\,{\rm{km}}$ and those on the tidal deformability from ${\tilde{{\rm{\Lambda }}}}_{1.186}\lt 720$ to ${\tilde{{\rm{\Lambda }}}}_{1.186}=38{4}_{-158}^{+306}$ (90% confidence intervals and 95% upper limit) at the source-frame chirp mass ${ \mathcal M }=1.186\,{M}_{\odot }$ when compared to the LIGO-Virgo-KAGRA analysis with uniform priors. We also show that these priors can be used to perform model selection between binary neutron star and neutron star-black hole mergers; in the case of GW190425, the results provide only marginal evidence with a Bayes factor ${ \mathcal B }{ \mathcal F }=1.33$ in favor of the binary neutron star merger hypothesis. Given their ability to improve the astrophysical inference of binary mergers involving neutron stars, we advocate for these physics-informed priors to be used as standard in the literature and provide open-source code for reproducibility and adaptation of the method.