Abstract

Binary neutron star (BNS) mergers are an important tool for studying nuclear matter at extreme densities inaccessible to laboratory experiments. The equation of state (EOS) of this nuclear matter affects the inspiral dynamics, remnant properties, and the resulting gravitational-wave signal, but remains only weakly constrained at supranuclear densities. The observation of  GW170817 provided observational constraints on the EOS and established multimessenger astrophysics as a probe of dense matter. Simulating BNS mergers across a range of EOSs and comparing the resulting observables against detections helps narrowing this uncertainty further, and is the broader motivation for this thesis. General relativistic magnetohydrodynamic simulations are the standard tool for modeling these mergers, and each simulation begins from quasi-equilibrium initial data (ID), which describes binary's gravitational and matter fields at the start of the simulation and must satisfy the Einstein constraint equations. The accuracy of this ID directly affects the reliability of the subsequent evolution and of any EOS constraints derived from it. In this thesis, we study how the accuracy and early-time dynamical stability of BNS ID depend on the EOS and the spectral resolution used to generate it. We generate ID for equal-mass, non-spinning binary neutron stars at different spectral resolutions for a polytropic EOS and a tabulated finite-temperature EOS using the FUKA ID solver. We then evolve selected configurations with the Einstein Toolkit using three different spacetime formulations. We find that the constraint violations converge exponentially with resolution for both EOSs, with the tabulated EOS showing relatively larger violations due to its non-smooth nature. By evolving the same initial data with different spacetime formulations, we separate the effects of the evolution scheme from the accuracy of the ID.

Publication Date

8-2026

Document Type

Thesis

Student Type

Graduate

Degree Name

Astrophysical Sciences and Technology (MS)

Department, Program, or Center

Physics and Astronomy, School of

College

College of Science

Advisor

Joshua Faber

Advisor/Committee Member

Yosef Zlochower

Advisor/Committee Member

Richard O’Shaughnessy

Campus

RIT – Main Campus

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