Orbits, forces and accretion dynamics near spinning black holes

TL;DR

This paper investigates the relativistic dynamics of circular orbits near spinning black holes, revealing peculiar orbital behaviors and their implications for accretion disk stability.

Contribution

It provides a detailed analysis of orbital properties in Kerr spacetime, highlighting counterintuitive phenomena and their physical explanations.

Findings

Orbital peculiarities near the horizon are clarified.

Implications for the stability of accretion disks are discussed.

Dynamics are analyzed using local observer measurements.

Abstract

We analyze the relativistic dynamical properties of Keplerian and non-Keplerian circular orbits in a general axisymmetric and stationary gravitational field, and discuss the implications for the stability of co- and counter-rotating accretion disks and tori surrounding a spinning black hole. Close to the horizon there are orbital peculiarities which can seem counterintuitive, but are elucidated by formulating the dynamics in terms of the orbital velocity actually measured by a local, zero-angular-momentum observer.