A Web Tool for Visualizing Kerr Spacetime and Bound Geodesics

The purpose of this web tool is to be an educational resource by providing visualization of the dynamics of test particles in Kerr spacetime. Many packages made to model Kerr geodesics do so by parameterizing the trajectory by the constants of motion: E, Lz, and Q. However, it can be difficult for a user to determine the combinations of values for these parameters that will result in interesting orbits. This Javascript program parameterizes trajectories in terms of the black hole spin a, semi-latus rectum p, eccentricity e, and inclination parameter x. The program dynamically calculates a parameter boundary for marginally-stable orbits. This allows the user to explore a range of stable, bound orbits. Additional features, such as Zero Angular Momentum Observers (ZAMOs), various camera options, fundamental orbital frequencies, and proper-time tracking, provide an engaging environment to help students gain intuition about geodesic motion including concepts such as frame-dragging.