# Coping with Junk Radiation in Binary Black Hole Simulations

## TL;DR

This paper investigates the impact of spurious junk radiation in binary black hole simulations, providing methods to estimate and correct its effects on initial parameters to improve gravitational wave template accuracy.

## Contribution

It introduces fitting formulas based on single black hole simulations to estimate and adjust for junk radiation effects in binary black hole initial data.

## Key findings

- Junk radiation effects are localized near black holes.
- Fitting formulas can estimate changes in mass and spin due to junk radiation.
- Adjusted initial parameters improve waveform accuracy for high SNR LIGO sources.

## Abstract

Spurious junk radiation in the initial data for binary black hole numerical simulations has been an issue of concern. The radiation affects the masses and spins of the black holes, modifying their orbital dynamics and thus potentially compromising the accuracy of templates used in gravitational wave analysis. Our study finds that junk radiation effects are localized to the vicinity of the black holes. Using insights from single black hole simulations, we obtain fitting formulas to estimate the changes from junk radiation on the mass and spin magnitude of the black holes in binary systems. We demonstrate how these fitting formulas could be used to adjust the initial masses and spin magnitudes of the black holes, so the resulting binary has the desired parameters after the junk radiation has left the computational domain. A comparison of waveforms from raw simulations with those from simulations that have been adjusted for junk radiation demonstrate that junk radiation could have an appreciable effect on the templates for LIGO sources with SNRs above 30.