An updated nuclear-physics and multi-messenger astrophysics framework for binary neutron star mergers

TL;DR

This paper introduces an enhanced computational framework, NMMA, that integrates nuclear physics and multi-messenger astrophysics to analyze neutron star mergers across gravitational waves, electromagnetic signals, and dense matter physics.

Contribution

The paper presents an extension of the NMMA framework for simultaneous analysis of gravitational-wave, kilonova, and gamma-ray burst data from neutron star mergers.

Findings

Estimated neutron star radius: 11.98 km with uncertainties.

Integrated multi-messenger data improves constraints on dense matter.

Demonstrated the framework's capability to combine diverse observational data.

Abstract

The multi-messenger detection of the gravitational-wave signal GW170817, the corresponding kilonova AT2017gfo and the short gamma-ray burst GRB170817A, as well as the observed afterglow has delivered a scientific breakthrough. For an accurate interpretation of all these different messengers, one requires robust theoretical models that describe the emitted gravitational-wave, the electromagnetic emission, and dense matter reliably. In addition, one needs efficient and accurate computational tools to ensure a correct cross-correlation between the models and the observational data. For this purpose, we have developed the Nuclear-physics and Multi-Messenger Astrophysics framework NMMA. The code allows incorporation of nuclear-physics constraints at low densities as well as X-ray and radio observations of isolated neutron stars. In previous works, the NMMA code has allowed us to constrain the equation of state of supranuclear dense matter, to measure the Hubble constant, and to compare dense-matter physics probed in neutron-star mergers and in heavy-ion collisions, and to classify electromagnetic observations and perform model selection. Here, we show an extension of the NMMA code as a first attempt of analyzing the gravitational-wave signal, the kilonova, and the gamma-ray burst afterglow simultaneously. Incorporating all available information, we estimate the radius of a $1.4M_\odot$ neutron star to be $R=11.98^{+0.35}_{-0.40}$km.