A Python Interface for Numerical Relativity Program AMSS-NCKU

TL;DR

AMSS-NCKU provides a powerful numerical relativity tool but its workflow remains relatively complex; this paper presents a Python interface that automates input generation, simulation execution, and visualization to simplify end-to-end runs. The approach adds a user-friendly Python script (AMSSNCKUInput.py) and an interactive terminal interface, enabling reproducible workflows with minimal manual reconfiguration. The authors validate the method on binary and triple black hole mergers, obtaining stable, physically consistent outputs such as orbital dynamics and gravitational-wave signals, with plots automatically produced from the simulation data. This work lowers entry barriers for new users and sets the stage for future extensions, including post-Newtonian dynamics and NSBH coalescences, by leveraging the Python ecosystem to broaden applicability in numerical relativity and gravitational-wave studies.

Abstract

Numerical relativity has produced profound and extensive impacts on modern astrophysics and gravitational-wave astronomy. In this work, we develop a Python interface for the numerical relativity program AMSS-NCKU. This interface enables the automation of initializing and executing the AMSS-NCKU simulations, as well as the automated visualization of the output data. To show the practical utility of this Python interface, we present two representative examples of numerical relativity simulations (the binary and triple black hole merger processes), obtaining well-behaved stable numerical results and the expected physical behaviors for black hole systems. The Python operational interface significantly reduces the operational complexity of the AMSS-NCKU simulation workflow, lowering the technical barriers for freshman users. Keywords: Numerical Relativity, Gravitational Waves, Black Hole Physics, Python

Figures (3)

• Figure 1: An illustration of the user-friendly interactive interface through the terminal output window in our Python interface for AMSS-NCKU.
• Figure 2: The dynamical evolution of a coalescing binary black hole system (with mass ratio $q = m_{1}/m_{2} = 1$). The black hole's orbit and gravitational wave $\Psi_{4}$ is presented in the upper panel. The 2D density plot of the conformal factor in spatial metric (before and after merge) is given in the middle panel. The 3D plot of Hamilton constraint violation (before and after merge) is shown in the lower panel.
• Figure 3: The dynamical evolution of a triple black hole system (with mass ratio $m_{1}:m_{2}:m_{3} = 36:29:20$, and the initial position of third black hole is located at the original point of coordinate system). The black hole's orbit and gravitational wave $\Psi_{4}$ is presented in the upper panel. The 2D density plot of the conformal factor in spatial metric (before and after merge) is given in the middle panel. The 3D plot of Hamilton constraint violation (before and after merge) is shown in the lower panel.