Numerical evolution of radiative Robinson-Trautman spacetimes

TL;DR

This paper investigates the numerical evolution of radiative Robinson-Trautman spacetimes, focusing on how matter spheroids emit gravitational and null radiation, leading to mass loss and increased gravitational wave amplitude.

Contribution

It introduces a numerical method to model the evolution of spheroidal matter emitting gravitational and null radiation in Robinson-Trautman spacetimes, highlighting the effects on gravitational wave amplitude and mass extraction.

Findings

Null radiation decreases over time, leading to Schwarzschild as the final state.

Emission of both gravitational and null radiation enhances gravitational wave amplitude.

Mass is extracted from the system through combined radiation emission.

Abstract

The evolution of spheroids of matter emitting gravitational waves and null radiation field is studied in the realm of radiative Robinson-Trautman spacetimes. The null radiation field is expected in realistic gravitational collapse, and can be either an incoherent superposition of waves of electromagnetic, neutrino or massless scalar fields. We have constructed the initial data identified as representing the exterior spacetime of uniform and non-uniform spheroids of matter. By imposing that the radiation field is a decreasing function of the retarded time, the Schwarzschild solution is the asymptotic configuration after an intermediate Vaidya phase. The main consequence of the joint emission of gravitational waves and the null radiation field is the enhancement of the amplitude of the emitted gravitational waves. Another important issue we have touched is the mass extraction of the bounded configuration through the emission of both types of radiation.