Decline of the Current Quadrupole Moment during the Merger Phase of Binary Black Hole Coalescence

Fan Zhang

doi:10.3390/universe6010003

Abstract

Utilizing the tools of tendex and vortex, we study the highly dynamic plunge and merger phases of several π -symmetric binary black hole coalescences. In particular, we observe a decline of the strength of the current quadrupole moment compared to that of the mass quadrupole moment during the merger phase, contrary to a naive estimate according to the dependence of these moments on the separation between the black holes. We further show that this decline of the current quadrupole moment is achieved through the remnants of the two individual spins becoming nearly aligned or anti-aligned with the total angular momentum. We also speculate on the ability to achieve a consistency between the electric and magnetic parity quasinormal modes.

Highlights

Binary black hole (BBH) coalescences constitute one of the most important types of gravitational wave sources for the network of gravitational-wave detectors, such as the Advanced LIGO [1], Virgo [2,3], GEO [4], and KAGRA [5], with the first observational detection of gravitational waves coming from precisely such a binary [6]
The merger phase dynamics are interesting because they reflect strong gravity behaviors and correspond to a large gravitational wave amplitude
The particular aspect of the merger phase dynamics we examine is the decline of the current quadrupole moment relative to the mass quadrupole moment in the near zone

Summary

Introduction

Binary black hole (BBH) coalescences constitute one of the most important types of gravitational wave sources for the network of gravitational-wave detectors, such as the Advanced LIGO [1], Virgo [2,3], GEO [4], and KAGRA [5], with the first observational detection of gravitational waves coming from precisely such a binary [6]. We use the knowledge gained to study these quantities in the SK simulation, and show that the current quadrupole declines in relative importance against the mass quadrupole during the merger phase. All the simulations and visualizations are performed with the Spectral Einstein Code (SpEC) [14] infrastructure

Vorticity from the Mass and Current Quadrupoles

Avenue for the Exit of the Current Quadrupole

Visualizing the Remnant Spins

Discussion