New approach to calculating the News

TL;DR

This paper introduces a new computational method for calculating gravitational radiation (news) in numerical relativity simulations using null-cone coordinates, demonstrating second order convergence in test cases.

Contribution

The paper develops and implements a coordinate transformation-based method for computing the news in characteristic numerical relativity simulations, with validated convergence results.

Findings

Method achieves second order convergence to analytic news values.

Successfully applied to test problems demonstrating effectiveness.

Provides a practical approach for gravitational wave extraction in simulations.

Abstract

We consider the problem of finding the gravitational radiation output, or news, within the context of a numerical simulation of a spacetime by means of the null-cone, or characteristic, approach to numerical relativity. We develop a method for computing the news that uses an explicit coordinate transformation to a coordinate system that satisfies the Bondi conditions. The method has been implemented computationally. We present results of applying the method to certain test problems, demonstrating second order convergence of the news to the analytic value.