Cross section, final spin and zoom-whirl behavior in high-energy black hole collisions

TL;DR

This paper investigates high-energy black hole collisions, revealing zoom-whirl behavior, near-maximal spin of the remnant, and significant energy radiation, advancing understanding of black hole dynamics in extreme conditions.

Contribution

It demonstrates zoom-whirl behavior in high-energy black hole collisions and quantifies the spin and energy radiated near the merger threshold.

Findings

Zoom-whirl behavior occurs near impact parameter threshold.

Remnant black hole can have near-maximal spin (a/M ~ 0.95).

Up to 35% of energy is radiated during collision.

Abstract

We study the collision of two highly boosted equal mass, nonrotating black holes with generic impact parameter. We find such systems to exhibit zoom-whirl behavior when fine tuning the impact parameter. Near the threshold of immediate merger the remnant black hole Kerr parameter can be near maximal (a/M about 0.95) and the radiated energy can be as large as 35% of the center-of-mass energy.