Super-Penrose process for extremal rotating neutral white holes

TL;DR

This paper demonstrates that extremal rotating white holes can facilitate a super-Penrose process, allowing particles to achieve unbounded energies and transfer high energy fluxes between universes, extending previous Kerr metric findings.

Contribution

It shows that white holes can enable unbounded energy extraction through the super-Penrose process, generalizing prior results for Kerr black holes.

Findings

Super-Penrose process is possible near extremal rotating white holes.

White holes can act as sources of high energy fluxes transferring between universes.

The process extends previous Kerr metric results to more general black hole solutions.

Abstract

We consider collision of two particles 1 and 2 near the horizon of the extremal rotating axially symmetric neutral generic black hole producing particles 3 and 4. We discuss the scenario in which both particles 3 and 4 fall into a black hole and move in a white hole region. If particle 1 is fine-tuned, the energy $E_{c.m.}$ in the centre of mass grows unbounded (the Ba\~{n}ados-Silk-West effect). Then, particle 3 \ can, in principle, reach a flat infinity in another universe. If not only $E_{c.m.}$ but also the corresponding Killing energy $E$ is unbounded, this gives a so-called super-Penrose process (SPP). We show that the SPP\ is indeed possible. Thus white holes turn out to be potential sources of high energy fluxes that transfers from one universe to another. This generalizes recent observaitons made by Patil and Harada for the Kerr metric. We analyze two different regimes of the process on different scales.