Disk collapse in general relativity

TL;DR

This paper investigates the complex process of relativistic disk collapse, black hole formation, and gravitational wave emission using numerical relativity, providing insights into strong-field gravity phenomena.

Contribution

It presents the first detailed numerical relativity simulations of relativistic disk collapse, exploring instabilities, waveforms, and black hole formation.

Findings

Ring instabilities can be suppressed by velocity dispersion.

Oscillating disks produce detectable gravitational waveforms.

Collapse simulations demonstrate black hole formation from disks.

Abstract

The radial collapse of a homogeneous disk of collisionless particles can be solved analytically in Newtonian gravitation. To solve the problem in general relativity, however, requires the full machinery of numerical relativity. The collapse of a disk is the simplest problem that exhibits the two most significant and challenging features of strong-field gravitation: black hole formation and gravitational wave generation. We carry out dynamical calculations of several different relativistic disk systems. We explore the growth of ring instabilities in equilibrium disks, and how they are suppressed by sufficient velocity dispersion. We calculate wave forms from oscillating disks, and from disks that undergo gravitational collapse to black holes. Studies of disk collapse to black holes should also be useful for developing new techniques for numerical relativity, such as apparent horizon boundary conditions for black hole spacetimes.