Astrophysical Measurement of the Equation of State of Neutron Star Matter

TL;DR

This paper reports the first astrophysical measurement of the pressure of cold neutron star matter above nuclear saturation density, challenging existing nucleonic equations of state.

Contribution

It provides the first measurement of neutron star matter pressure at high densities using observational data, offering new constraints for nuclear physics models.

Findings

Pressure below nucleonic EOS predictions at high densities

Challenges existing microscopic theories of neutron star matter

Uses mass and radius data of three neutron stars

Abstract

We present the first astrophysical measurement of the pressure of cold matter above nuclear saturation density, based on recently determined masses and radii of three neutron stars. The pressure at higher densities are below the predictions of equations of state that account only for nucleonic degrees of freedom, and thus present a challenge to the microscopic theory of neutron star matter.