scholarly journals Energy extraction from Kerr black holes by rigidly rotating strings

2016 ◽  
Vol 94 (12) ◽  
Author(s):  
Shunichiro Kinoshita ◽  
Takahisa Igata ◽  
Kentaro Tanabe
Keyword(s):  
Black Holes ◽  
Energy Extraction ◽  
Kerr Black Holes

Effect of charge and deformation parameter on energy extraction in charged non-Kerr black holes

2019 ◽  
Vol 28 (16) ◽  
pp. 2040012
Author(s):  
Rehana Rahim ◽  
Khalid Saifullah
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Deformation Parameter ◽  
High Efficiency ◽  
Process Efficiency ◽  
Energy Extraction ◽  
Penrose Process ◽  
Kerr Black Holes ◽  
Very High

We analyze the charged Johannsen–Psaltis black hole for energy extraction via the Penrose process. Efficiency of the Penrose process is found to be dependent on the deformation parameter of the metric and charge. Doing the calculations numerically, we find that, in the nonextremal limit, presence of charge leads to lesser efficiency than the Kerr. In the extremal cases with negative deformation parameter, charge leads to a very high efficiency, higher than that of the Kerr and Johannsen–Psaltis black holes.

scholarly journals Growth of accretion driven scalar hair around Kerr black holes

2021 ◽  
Vol 103 (4) ◽  
Author(s):  
Jamie Bamber ◽  
Katy Clough ◽  
Pedro G. Ferreira ◽  
Lam Hui ◽  
Macarena Lagos
Keyword(s):  
Black Holes ◽  
Scalar Hair ◽  
Kerr Black Holes

scholarly journals Second-order perturbations of Kerr black holes: Formalism and reconstruction of the first-order metric

2021 ◽  
Vol 103 (10) ◽  
Author(s):  
Nicholas Loutrel ◽  
Justin L. Ripley ◽  
Elena Giorgi ◽  
Frans Pretorius
Keyword(s):  
Black Holes ◽  
Second Order ◽  
First Order ◽  
Kerr Black Holes

scholarly journals Aschenbach effect: Unexpected topology changes in the motion of particles and fluids orbiting rapidly rotating Kerr black holes

2005 ◽  
Vol 71 (2) ◽  
Author(s):  
Zdeněk Stuchlík ◽  
Petr Slaný ◽  
Gabriel Török ◽  
Marek A. Abramowicz
Keyword(s):  
Black Holes ◽  
Topology Changes ◽  
Kerr Black Holes

scholarly journals Initial data for perturbed Kerr black holes on hyperboloidal slices

2014 ◽  
Vol 31 (16) ◽  
pp. 165001 ◽  
Author(s):  
David Schinkel ◽  
Rodrigo Panosso Macedo ◽  
Marcus Ansorg
Keyword(s):  
Black Holes ◽  
Initial Data ◽  
Kerr Black Holes

scholarly journals ENERGY EXTRACTION FROM GRAVITATIONAL COLLAPSE TO STATIC BLACK HOLES

2003 ◽  
Vol 12 (01) ◽  
pp. 121-127 ◽  
Author(s):  
REMO RUFFINI ◽  
LUCA VITAGLIANO
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Extraction Process ◽  
Maximum Efficiency ◽  
Energy Extraction ◽  
Mass Energy ◽  
Classical Level ◽  
Static Black Hole ◽  
Exact Analytic Expression ◽  
Analytic Expression

The mass-energy formula of black holes implies that up to 50% of the energy can be extracted from a static black hole. Such a result is reexamined using the recently established analytic formulas for the collapse of a shell and the expression for the irreducible mass of a static black hole. It is shown that the efficiency of energy extraction process during the formation of the black hole is linked in an essential way to the gravitational binding energy, the formation of the horizon and the reduction of the kinetic energy of implosion. Here a maximum efficiency of 50% in the extraction of the mass energy is shown to be generally attainable in the collapse of a spherically symmetric shell: surprisingly this result holds as well in the two limiting cases of the Schwarzschild and extreme Reissner–Nordström space–times. Moreover, the analytic expression recently found for the implosion of a spherical shell to an already formed black hole leads to a new exact analytic expression for the energy extraction which results in an efficiency strictly less than 100% for any physical implementable process. There appears to be no incompatibility between General Relativity and Thermodynamics at this classical level.

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