Parameter estimation for strong phase transitions in supranuclear matter using gravitational-wave astronomy

TL;DR

This paper introduces a new method to detect strong phase transitions in supranuclear matter within neutron stars using gravitational-wave signals, demonstrating that a small number of observations could confirm their presence.

Contribution

It develops a novel parameterization of the supranuclear equation of state enabling detection of phase transitions solely from gravitational-wave data.

Findings

Twelve events may suffice to verify strong phase transitions with current detectors.

No evidence of phase transitions was found in GW170817 and GW190425.

Method successfully distinguishes equations of state with and without phase transitions.

Abstract

At supranuclear densities, explored in the core of neutron stars, a strong phase transition from hadronic matter to more exotic forms of matter might be present. To test this hypothesis, binary neutron-star mergers offer a unique possibility to probe matter at densities that we can not create in any existing terrestrial experiment. In this work, we show that, if present, strong phase transitions can have a measurable imprint on the binary neutron-star coalescence and the emitted gravitational-wave signal. We construct a new parameterization of the supranuclear equation of state that allows us to test for the existence of a strong phase transition and extract its characteristic properties purely from the gravitational-wave signal of the inspiraling neutron stars. We test our approach using a Bayesian inference study simulating 600 signals with three different equations of state and find that for current gravitational-wave detector networks already twelve events might be sufficient to verify the presence of a strong phase transition. Finally, we use our methodology to analyze GW170817 and GW190425, but do not find any indication that a strong phase transition is present at densities probed during the inspiral.