In a series of previous works, several initial boundary value problems in numerical relativity were demonstrated as numerically stable even with boundaries placed in the strongly gravitating region of a dynamical spacetime. Now, care is being taken to define boundary conditions that can be placed on the radiating degrees of freedom based on quasi-local conservation laws. Incoming gravitational...
Numerical relativity (NR) has revolutionized our understanding of strong-field gravity, enabling high-fidelity simulations of compact binary systems. This paper reviews recent breakthroughs in NR methodologies, with emphasis on binary neutron star (BNS) and black hole–neutron star (BHNS) mergers. We discuss advancements in adaptive mesh refinement, constraint-damping formulations, and...
Functions of bound Kerr geodesic motion play a central role in many calculations in relativistic astrophysics, ranging from gravitational-wave generation to self-force and radiation-reaction modeling. Although these functions can be expressed as a Fourier series using the geodesic fundamental frequencies, reconstructing them in coordinate time is challenging due to the coupling of the radial...
In the realm of general relativity, given two metric solutions in different gauges, determining whether they describe the same physical scenario poses significant challenges. This study proposes a novel application of machine learning techniques to address this issue within the context of numerical relativity. We introduce the first implementation of neural networks to learn the mapping...
In this work, we perform the first fully three-dimensional simulations of the ekpyrotic cosmological scenario. Our numerical relativity code is based on previous work that assumed some symmetry. In particular, we use a tetrad formulation of the Einstein-scalar field equations, but in this case using the parallel infrastructure PAMR. Our goal is to test the robustness of the ekpyrotic...
Many binary population-synthesis (BPS) codes have been developed over the last few decades to evolve binary stars throughout their entire evolutionary history. BPS codes are extremely useful for investigating astrophysical processes we observe in the universe such as supernovae, x-ray binaries, generation of r-process elements, and gravitational-wave populations. However, many current BPS...
