Universality of BSW mechanism for spinning particles

Abstract

Bañados et al. (BSW) found that Kerr black holes can act as particle accelerators with collisions at arbitrarily high center-of-mass energies. Recently, collisions of particles with spin around some rotating black holes have been discussed. In this paper, we study the BSW mechanism for spinning particles by using a metric ansatz which describes a general rotating black hole. We notice that there are two inequivalent definitions of center-of-mass (CM) energy for spinning particles. We mainly discuss the CM energy defined in terms of the worldline of the particle. We show that there exists an energy-angular momentum relation e = h j that causes collisions with arbitrarily high energy near extremal black holes. We also provide a simple but rigorous proof that the BSW mechanism breaks down for nonextremal black holes. For the alternative definition of the CM energy, some authors find a new critical spin relation that also causes the divergence of the CM mass. However, by checking the timelike constraint, we show that particles with this critical spin cannot reach the horizon of the black hole. Further numerical calculation suggests that such particles cannot exist anywhere outside the horizon. Our results are universal, independent of the underlying theories of gravity.

Exploring black holes as particle accelerators: hoop-radius, target particles and escaping conditions

“…This collisional Penrose process has been studied for different black hole scenarios, such as non-extremal Kerr [3][4][5][6], Kerr-(anti)de Sitter [7,8], Reissner-Nordström [9,10], and Kerr-Newman [11][12][13] geometries, reproducing the original BSW result. Also, taking into account the spin or the charge of the particles, one still obtains an arbitrarily high center of mass energy for collisions near to the horizon of rotating black holes [14][15][16][17]. For non-rotating black holes this feature is absent [18], as long as the colliding particles fall towards the black hole from large (infinite) radial distance.…”

Collisional Penrose process of 4D rotational Einstein-Gauss-Bonnet black holes *

“…After that, the BSW mechanism was extended to spinning particles [33][34][35][36][37][38][39][40][41][42][43]. Besides, we know that spinning particles are no longer moving along geodesics in curved spacetime and the motion of spinning test particles can be described by modified equations [44][45][46][47][48]. In Ref.…”

Schwarzschild black hole surrounded by quintessential matter field as an accelerator for spinning particles

“…They finally concluded that the spin parameter (a) and the charge (Q) of the BH affect the CM energy of the colliding particles in a completely opposite way. Recently, the universality of BSW mechanism for spinning particle, for a class of stationary axisymmetric BH is also discussed in [105]. However, the study of BHs as particle accelerators for spinning particles has been performed for only a few BH models.…”