scholarly journals Radiative Penrose process: Energy gain by a single radiating charged particle in the ergosphere of rotating black hole

2021 ◽  
Vol 103 (2) ◽  
Author(s):  
Martin Kološ ◽  
Arman Tursunov ◽  
Zdeněk Stuchlík
Keyword(s):  
Black Hole ◽  
Charged Particle ◽  
Energy Gain ◽  
Rotating Black Hole ◽  
Penrose Process ◽  
Process Energy

Super-Penrose process

2020 ◽  
Vol 35 (02n03) ◽  
pp. 2040058
Author(s):  
O. B. Zaslavskii
Keyword(s):  
Black Hole ◽  
Flat Space ◽  
Space Time ◽  
Centre Of Mass ◽  
Rotating Black Hole ◽  
Mass Frame ◽  
Penrose Process ◽  
Energy Formula ◽  
Full Classification

If two particles collide near a rotating black hole, their energy in the centre of mass frame can become unbounded under certain conditions. In doing so, the Killing energy [Formula: see text] of debris at infinity is, in general, remain restricted. If [Formula: see text] is also unbounded, this is called the super-Penrose process. We elucidate when such a process is possible and give full classification of corresponding relativistic objects for rotating space-times. We also discuss the case of a pure electric super-Penrose process that is valid even in the flat space-time. The key role in consideration is played by the Wald inequalities.

scholarly journals Particles with Negative Energies in Nonrelativistic and Relativistic Cases

Symmetry ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 528
Author(s):  
Andrey A. Grib ◽  
Yuri V. Pavlov
Keyword(s):  
Black Hole ◽  
Coordinate System ◽  
Space Time ◽  
De Sitter ◽  
Relativistic Case ◽  
Nonrelativistic Case ◽  
Rotating Black Hole ◽  
Minkowski Space Time ◽  
Penrose Process ◽  
Penrose Effect

States of particles with negative energies are considered for the nonrelativistic and relativistic cases. In the nonrelativistic case it is shown that the decay close to the attracting center can lead to the situation similar to the Penrose effect for a rotating black hole when the energy of one of the fragments is larger than the energy of the initial body. This is known as the Oberth effect in the theory of the rocket movement. The realizations of the Penrose effect in the non-relativistic case in collisions near the attracting body and in the evaporation of stars from star clusters are indicated. In the relativistic case similar to the well known Penrose process in the ergosphere of the rotating black hole it is shown that the same situation as in ergosphere of the black hole occurs in rotating coordinate system in Minkowski space-time out of the static limit due to existence of negative energies. In relativistic cases differently from the nonrelativistic ones, the mass of the fragment can be larger than the mass of the decaying body. Negative energies for particles are possible in the relativistic case in cosmology of the expanding space when the coordinate system is used with a nondiagonal term in metrical tensor of the space-time. Friedmann metrics for three cases: open, close and quasieuclidian, are analyzed. The De Sitter space-time is shortly discussed.

scholarly journals Wandering of the central black hole in a galactic nucleus and correlation of the black hole mass with the bulge mass

2021 ◽  
Author(s):  
Hajime Inoue
Keyword(s):  
Black Hole ◽  
Loss Rate ◽  
Energy Gain ◽  
Stellar Disk ◽  
Black Hole Mass ◽  
Central Black Hole ◽  
Massive Black Hole ◽  
Stellar Cluster ◽  
Upper Limit ◽  
Simple Parameter

Abstract We investigate a mechanism for a super-massive black hole at the center of a galaxy to wander in the nucleus region. A situation is supposed in which the central black hole tends to move by the gravitational attractions from the nearby molecular clouds in a nuclear bulge but is braked via the dynamical frictions from the ambient stars there. We estimate the approximate kinetic energy of the black hole in an equilibrium between the energy gain rate through the gravitational attractions and the energy loss rate through the dynamical frictions in a nuclear bulge composed of a nuclear stellar disk and a nuclear stellar cluster as observed from our Galaxy. The wandering distance of the black hole in the gravitational potential of the nuclear bulge is evaluated to get as large as several 10 pc, when the black hole mass is relatively small. The distance, however, shrinks as the black hole mass increases, and the equilibrium solution between the energy gain and loss disappears when the black hole mass exceeds an upper limit. As a result, we can expect the following scenario for the evolution of the black hole mass: When the black hole mass is smaller than the upper limit, mass accretion of the interstellar matter in the circumnuclear region, causing the AGN activities, makes the black hole mass larger. However, when the mass gets to the upper limit, the black hole loses the balancing force against the dynamical friction and starts spiraling downward to the gravity center. From simple parameter scaling, the upper mass limit of the black hole is found to be proportional to the bulge mass, and this could explain the observed correlation of the black hole mass with the bulge mass.

scholarly journals Dynamics of the nonrotating and rotating black hole scalarization

2021 ◽  
Vol 103 (6) ◽  
Author(s):  
Daniela D. Doneva ◽  
Stoytcho S. Yazadjiev
Keyword(s):  
Black Hole ◽  
Rotating Black Hole
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