Observing an intermediate mass black hole GW190521 with minimal assumptions

TL;DR

This paper reports the detection of the gravitational wave GW190521, the heaviest binary black-hole merger observed, using a minimal-assumption, model-agnostic search algorithm, providing strong evidence for an intermediate-mass black hole.

Contribution

The paper demonstrates the effectiveness of the coherent WaveBurst (cWB) algorithm in detecting binary black holes without relying on signal templates, confirming GW190521's properties.

Findings

GW190521 is the heaviest binary black-hole merger detected.

cWB successfully detected GW190521 with minimal assumptions.

The reconstructed waveform is consistent with theoretical models.

Abstract

On May 21, 2019 Advanced LIGO and Advanced Virgo detectors observed a gravitational-wave transient GW190521, the heaviest binary black-hole merger detected to date with the remnant mass of 142$\,$M$_\odot$ that was published recently. This observation is the first strong evidence for the existence of intermediate-mass black holes. The significance of this observation was determined by the coherent WaveBurst (cWB) - search algorithm, which identified GW190521 with minimal assumptions on its source model. In this paper, we demonstrate the capabilities of cWB to detect binary black holes without use of the signal templates, describe the details of the GW190521 detection and establish the consistency of the model-agnostic reconstruction of GW190521 by cWB with the theoretical waveform model of a binary black hole.