gr-Orbit-Toolkit: A Python-Based Software for Simulating and Visualizing Relativistic Orbits

TL;DR

The paper introduces gr-orbit-toolkit, a Python software for simulating classical and relativistic orbits, demonstrating its effectiveness in educational and research contexts, especially near strong gravitational fields.

Contribution

It presents a new Python-based toolkit for simulating relativistic orbits using numerical integration, with validation and applications in astrophysics and education.

Findings

Relativistic and classical orbits differ near Schwarzschild radius.

The toolkit accurately captures relativistic orbital precession.

Simulations are numerically robust and suitable for teaching and research.

Abstract

Creating software dedicated to simulation is essential for teaching and research in Science, Technology, Engineering, and Mathematics (STEM). Physics lecturing can be more effective when digital twins are used to accompany theory classes. Research in physics has greatly benefited from the advent of modern, high-level programming languages, which facilitate the implementation of user-friendly code. Here, we report our own Python-based software, the gr-orbit-toolkit, to simulate orbits in classical and general relativistic scenarios. First, we present the ordinary differential equations (ODEs) for classical and relativistic orbital accelerations. For the latter, we follow a post-Newtonian approach. Second, we describe our algorithm, which numerically integrates these ODEs to simulate the orbits of small-sized objects orbiting around massive bodies by using Euler and Runge-Kutta methods. Then, we study a set of sample two-body models with either the Sun or a black hole in the center. Our simulations confirm that the orbital motions predicted by classical and relativistic ODEs drastically differ for bodies near the Schwarzschild radius of the central massive body. Classical mechanics explains the orbital motion of objects far away from a central massive body, but general relativity is required to study objects moving at close proximity to a massive body, where the gravitational field is strong. Our study on objects with different eccentricities confirms that our code captures relativistic orbital precession. Our convergence analysis shows the toolkit is numerically robust. Our gr-orbit-toolkit aims at facilitating teaching and research in general relativity, so a comprehensive user and developer guide is provided in the public code repository.