Problematic systematics in neutron-star merger simulations

TL;DR

This paper identifies a significant systematic error in neutron-star merger simulations caused by artificial shock heating, which impacts the accuracy of gravitational-wave models crucial for understanding dense nuclear matter.

Contribution

It reveals a problematic systematic error in finite-temperature merger simulations and discusses its impact on gravitational-wave signal modeling.

Findings

Artificial shock heating leads to elevated temperatures in simulations.

Systematic errors significantly affect tidal parameter calculations.

Addressing these errors is essential for robust gravitational-wave models.

Abstract

Next-generation gravitational-wave instruments are expected to constrain the equation of state of dense nuclear matter by observing binaries involving neutron stars. We highlight a problematic systematic error in finite-temperature merger simulations, where shock heating associated with the neutron-star surface gives rise to elevated temperatures. We demonstrate the severe implications of this artificial heating by computing static and dynamical tidal parameters for neutron stars immersed in simulation temperature profiles. The induced systematic errors must be addressed if we want to build robust gravitational-wave signal models for neutron-star, or indeed neutron star-black hole, binaries.