Alternative possibility of GW190521: Gravitational waves from high-mass black hole-disk systems

We evolve high-mass disks of mass 15-50 M-circle dot orbiting a 50 M-circle dot spinning black hole in the framework of numerical relativity. Such high-mass systems could be an outcome during the collapse of rapidly rotating very massive stars. The massive disks are dynamically unstable to the so-called one-armed spiral-shape deformation with the maximum fractional density perturbation of delta rho/rho greater than or similar to 0.1, and hence, high-amplitude gravitational waves are emitted. The waveforms are characterized by an initial high-amplitude burst with the frequency of similar to 40-50 Hz and the maximum amplitude of (1-10) x 10(-22) at the hypothetical distance of 100 Mpc and by a subsequent low-amplitude quasiperiodic oscillation. We illustrate that the waveforms in our models with a wide range of the disk mass resemble that of GW190521. We also point out that gravitational waves from rapidly rotating very massive stars can be the source for 3rd-generation gravitational-wave detectors for exploring the formation process of rapidly spinning high-mass black holes of mass similar to 50-100 M-circle dot in an early universe.

Automated summary

In this study, high-mass disks orbiting a spinning black hole were found to be dynamically unstable, producing high-amplitude gravitational waves. The waveforms exhibit an initial burst followed by quasiperiodic oscillation, with characteristics resembling GW190521. These gravitational waves from rapidly rotating massive stars could serve as a source for 3rd-generation gravitational-wave detectors to explore the formation of high-mass black holes in the early universe.