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

Understand

We evolve high-mass disks of mass $15$-$50M_\odot$ orbiting a $50M_\odot$ 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 $\delta \rho/\rho \gtrsim 0.1$, and hence, high-amplitude gravitational waves are emitted.
• The waveforms are characterized by an initial high-amplitude burst with the frequency of $\sim 40$-$50$ Hz and the maximum amplitude of $(1$-$10)\times 10^{-22}$ at the hypothetical distance of 100 Mpc and by a subsequent low-amplitude quasi-periodic oscillation.