General relativistic rotational energy extraction from black holes-accretion disk systems

TL;DR

This paper investigates the extraction of rotational energy from black holes in accretion disk systems using relativistic models, relating energy extraction to spacetime properties, accretion configurations, and observable features.

Contribution

It introduces a novel approach linking energy extraction efficiency to spacetime light surfaces and accretion disk properties, predicting specific black hole spin parameters and dynamics.

Findings

Identifies key black hole spins a≈0.94M, a≈0.7M, and a≈0.3M.

Establishes relations between tori rotation laws, frequencies, and relativistic velocities.

Provides constraints on accretion disk configurations and energy extraction processes.

Abstract

We constrain the BHs spin with the evaluation of the dimensionless parameter \xi, the total rotational energy extracted versus the BH mass. The energy extraction can power an outflow which can be then observed. We relate the energy extraction to the accreting configurations and the accretion processes occurring in a cluster of corotating and counter-rotating tori orbiting one central Kerr SMBH, associating \xi to the accretion processes characteristics. We relate the regions of tori parameters to the energy extraction processes, binding \xi to properties of light surfaces by using the bundles, relating measures in different regions of the spacetimes. We evaluate properties of the BH accretions disks, and correlate spacetimes prior and after their transition due to the energy extraction. Light surfaces are related to the generators of Killing horizons, proving limiting frequency of the stationary observers of the geometries. We consider the photon limiting curves of the stationary observers as constraints for various processes regulated by these frequencies, to relate different BH states, prior and after the energy extraction, investigating regions close to the BH horizons and rotational axis. From methodological view-point we used a naked singularity -BH correspondence defined with metric bundles to predict the BH--accretion disk system observational characteristics. The analysis points relevant BH spins a\approx0.94M, a\approx 0.7M and a\approx0.3M. We show the relation between the rotational law of the tori, the bundle characteristic frequency and the relativistic velocity defining the von Zeipel surfaces. The inferior limit on the formation of corotating is \ell/a\geq2, for counter-rotating tori \ell/a\leq -22/5 (\ell is the fluids specific angular momentum).