Accurate extraction of the News

TL;DR

This paper introduces a new method for extracting gravitational waves from numerical spacetime simulations by transforming to Bondi coordinates and calculating the Bondi news function, improving accuracy and simplicity.

Contribution

The paper presents a novel scheme for gravitational wave extraction using direct transformation to Bondi coordinates, simplifying calculations and enhancing accuracy over previous methods.

Findings

More accurate gravitational wave extraction in test problems.

Simplified calculations using ordinary differential equations.

Effective implementation with uniform Bondi angular grid.

Abstract

We propose a new scheme for extracting gravitational radiation from a characteristic numerical simulation of a spacetime. This method is similar in conception to our earlier work but analytical and numerical implementation is different. The scheme is based on direct transformation to the Bondi coordinates and the gravitational waves are extracted by calculating the Bondi news function in Bondi coordinates. The entire calculation is done in a way which will make the implementation easy when we use uniform Bondi angular grid at $\mathcal I^+$. Using uniform Bondi grid for news calculation has added advantage that we have to solve only ordinary differential equations instead of partial differential equation. For the test problems this new scheme allows us to extract gravitational radiation much more accurately than the previous schemes.