Collision of an object in the transition from adiabatic inspiral to plunge around a Kerr black hole

Understand

An inspiralling object of mass $\mu$ around a Kerr black hole of mass $M (\gg \mu)$ experiences a continuous transition near the innermost stable circular orbit from adiabatic inspiral to plunge into the horizon as gravitational radiation extracts its energy and angular momentum.

• We investigate the collision of such an object with a generic counterpart around a Kerr black hole.
• We find that the angular momentum of the object is fine-tuned through gravitational radiation and that the high-velocity collision of the object with a generic counterpart naturally occurs around a nearly maximally rotating black hole.
• We also find that the centre-of-mass energy can be far beyond the Planck energy for dark matter particles colliding around a stellar mass black hole and as high as $10^{58}$ erg for stellar mass compact objects colliding around a supermassive black hole, where the present transition formalism is well justified.