Center of mass energy of colliding electrically neutral particles and super-Penrose process

Abstract

We consider collisions of electrically neutral particles in the background of axially symmetric rotating space-times. For reactions of the kind 1+2→3+4 we give full classification of possible scenarios based on exact expressions for dynamic characteristics of particles 3 and 4 depending on particles 1 and 2. There are five nonequivalent scenarios valid for different types of space-time (black hole, naked singularity, etc.). We are mainly interested in the situations when particle collisions can give unbounded outcome for (i) the energy E c.m. in the centre of mass frame and (ii) Killing energy E at infinity. If (i) is fulfilled, this may or may not lead to (ii). If (ii) holds, this is called the super-Penrose process (SPP). For equatorial particle motion, we establish close relation between the type of behavior of E c.m. depending on the lapse function N in the point of collision and the possibility of the SPP. This unites separate previous observations in literature in a unified picture as a whole. In doing so, no explicit transformations to the centre of mass frame and back are needed, so all consideration is carried out in the original frame. As a result,we suggest classification of sub-classes of scenarios that are able (or unable) to give rise to the SPP particle collision, super-Penrose process, centre of mass frame.

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

“…First, that, for distant observers, the time until such a collision takes place close to the hoop radius of a black hole, can become arbitrarily large [18,28]. Second, that, if such high energetic collisions happen near the a black hole, the secondary products produced in such a collision may loose energy very quickly, due to multiple scatterings taking place before the particles can escape towards the Earth and be detected [29][30][31].…”

“…Other important limiting factors which one needs to take into account when searching for such high center of mass collisions near black holes are: the Thorne limit [25], which states that the spin of realistic astrophysical black holes is bounded from above [5,26,27]; the time which passes for an observer far away from the black hole, while the collision of two particles reaching the near horizon region of a black hole take place (this can be of order of the age of the universe) [18,28]; multiple scatterings and collisions of the particle(s) emerging after the collision near the black hole [29][30][31]. All of these phenomena need to be taken into account and are basically screening the existence of a collisional Penrose process or damping its effectiveness as a particle accelerator.…”

Super-Penrose process for extremal rotating neutral white holes

“…Nc . It was found in [23], where it was pointed out that it corresponds to falling both particles in a black hole, so it was put aside since we were interested in particles returning to infinity.…”

“…But now, it is this case that came into play. Therefore, we take advantage of formulas already derived in [23] but exploit them in a new context -see eqs. ( 35), (36) below.…”

Constraining LQG Graph with Light Surfaces: Properties of BH Thermodynamics for Mini-Super-Space, Semi-Classical Polymeric BH

“…The pre-horizon was analyzed in [14][15][16][17][18][19][20]. In these analyses, it was concluded that a gyroscope would conserve a memory of the static or stationary initial state, leading to the gravitational collapse of a mass distribution [14][15][16][17][18][19][20][21][22][23][24].…”