On white holes as particle accelerators

Understand

We analyze scenarios of particle collisions in the metric of a nonextremal black hole that can potentially lead to ultrahigh energy $E_{c.m.}$ in their centre of mass frame.

• Particle 1 comes from infinity to the black hole horizon while particle 2 emerges from a white hole region.
• It is shown that unbounded $E_{c.m.}$ $\ $require that particle 2 pass close to the bifurcation point.
• The analogy with collisions inside the horizon is discussed.