Constraining Neutron-Star Matter with Microscopic and Macroscopic Collisions

TL;DR

This paper combines astrophysical observations and heavy-ion collision experiments using Bayesian inference to better understand dense nuclear matter in neutron stars, revealing increased pressure estimates and larger radii consistent with recent data.

Contribution

It introduces a joint analysis framework integrating astrophysical and terrestrial data to constrain neutron-star matter properties more effectively.

Findings

Heavy-ion collision data increases pressure estimates in dense matter.

Neutron-star radii are shifted towards larger values.

Constraints from experiments and observations are highly consistent.

Abstract

Interpreting high-energy, astrophysical phenomena, such as supernova explosions or neutron-star collisions, requires a robust understanding of matter at supranuclear densities. However, our knowledge about dense matter explored in the cores of neutron stars remains limited. Fortunately, dense matter is not only probed in astrophysical observations, but also in terrestrial heavy-ion collision experiments. In this work, we use Bayesian inference to combine data from astrophysical multi-messenger observations of neutron stars and from heavy-ion collisions of gold nuclei at relativistic energies with microscopic nuclear theory calculations to improve our understanding of dense matter. We find that the inclusion of heavy-ion collision data indicates an increase in the pressure in dense matter relative to previous analyses, shifting neutron-star radii towards larger values, consistent with recent NICER observations. Our findings show that constraints from heavy-ion collision experiments show a remarkable consistency with multi-messenger observations and provide complementary information on nuclear matter at intermediate densities. This work combines nuclear theory, nuclear experiment, and astrophysical observations, and shows how joint analyses can shed light on the properties of neutron-rich supranuclear matter over the density range probed in neutron stars.