Kilonova Emission from Neutron Star Mergers with Different Equations of State

TL;DR

This study investigates how different neutron star equations of state influence the ejecta composition and brightness of kilonovae, providing insights for constraining neutron star properties through observations.

Contribution

It demonstrates the strong dependence of kilonova emission and nucleosynthesis on neutron star equations of state, linking EoS properties to observable kilonova features.

Findings

Softer EoS leads to more ejecta and brighter kilonova peaks.

EoS significantly affects r-process nucleosynthesis patterns.

Kilonova brightness can constrain neutron star EoS properties.

Abstract

Kilonova is an optical-infrared transient powered by the radioactive decay of heavy nuclei from binary neutron star mergers. Its observational characteristics depend on the mass and the nuclide composition of meger ejecta, which are sensitive to the equation of state (EoS) of neutron star. We use astrophysical conditions derived from different EoSs as nucleosynthesis inputs to explore the impact of various EoS on the $r$-process nucleosynthesis and the kilonova emission. Our results show that both the abundance patterns of merger ejecta and kilonova light curves are strongly dependent on the neutron star EoSs. Given the mass of two neutron stars, the merger with a softer EoS tends to generate a larger amount of ejected material, and may lead to a brighter kilonova peak luminosity. The relationship between the neutron star EoS and the peak luminosity provides a probe for constraining the properties of EoS in multi-messenger observations of neutron star mergers.