%0 Journal Article %T Extracting black-hole rotational energy: The generalized Penrose process %+ Institut d'Astrophysique de Paris (IAP) %A Lasota, J. -P. %A Gourgoulhon, E. %A Abramowicz, M. %A Tchekhovskoy, A. %A Narayan, R. %< avec comité de lecture %J Physical Review D %V 89 %8 2014 %D 2014 %Z 1310.7499 %Z 2014PhRvD..89b4041L %R 10.1103/PhysRevD.89.024041 %K 04.70.Bw %K 95.30.Sf %K 95.30.Qd %K 97.60.Lf %K Classical black holes %K Relativity and gravitation %K Magnetohydrodynamics and plasmas %K Black holes %K General Relativity and Quantum Cosmology %K Astrophysics - High Energy Astrophysical Phenomena %Z Sciences of the Universe [physics]Journal articles %X In the case involving particles, the necessary and sufficient condition for the Penrose process to extract energy from a rotating black hole is absorption of particles with negative energies and angular momenta. No torque at the black-hole horizon occurs. In this article we consider the case of arbitrary fields or matter described by an unspecified, general energy-momentum tensor Tμν and show that the necessary and sufficient condition for extraction of a black hole's rotational energy is analogous to that in the mechanical Penrose process: absorption of negative energy and negative angular momentum. We also show that a necessary condition for the Penrose process to occur is for the Noether current (the conserved energy-momentum density vector) to be spacelike or past directed (timelike or null) on some part of the horizon. In the particle case, our general criterion for the occurrence of a Penrose process reproduces the standard result. In the case of relativistic jet-producing "magnetically arrested disks," we show that the negative energy and angular-momentum absorption condition is obeyed when the Blandford-Znajek mechanism is at work, and hence the high energy extraction efficiency up to ∼300% found in recent numerical simulations of such accretion flows results from tapping the black hole's rotational energy through the Penrose process. We show how black-hole rotational energy extraction works in this case by describing the Penrose process in terms of the Noether current. %G English %2 https://insu.hal.science/insu-03645730/document %2 https://insu.hal.science/insu-03645730/file/PhysRevD.89.024041.pdf %L insu-03645730 %U https://insu.hal.science/insu-03645730 %~ INSU %~ CNRS %~ IAP %~ SORBONNE-UNIVERSITE %~ SU-INF-2018 %~ SU-SCIENCES %~ SU-TI %~ ALLIANCE-SU