Lense-Thirring effect on accretion flow from counter-rotating tori

TL;DR

This paper investigates the properties and location of the accretion flow's turning point from counter-rotating tori around Kerr black holes, emphasizing the influence of black hole spin and potential observability of the flow's corona.

Contribution

It characterizes the flow properties at the turning point, analyzes the corona's structure, and relates the flow dynamics to black hole spin and initial conditions, providing new insights into counter-rotating accretion flows.

Findings

Turning points are located in a narrow corona near the ergosurface.

The corona size varies with black hole spin and is larger on the equatorial plane.

Flow properties are largely independent of specific accretion details.

Abstract

We study the accretion flow from a counter-rotating torus orbiting a central Kerr black hole (BH). We characterize the flow properties at the turning point of the accreting matter flow from the orbiting torus, defined by the condition $u^\phi = 0$ on the flow torodial velocity. The counter-rotating accretion flow and jet-like flow turning point location along BH rotational axis is given. Some properties of the counter-rotating flow thickness and counter-rotating tori energetics are studied.The maximum amount of matter swallowed by the BH from the counter-rotating tori is determined by the background properties. The fast spinning BH energetics depends mostly on BH spin rather than on the properties of the counter-rotating fluids or the tori masses. The turning point is located in a narrow orbital corona (spherical shell), for photons and matter flow constituents, surrounding the BH stationary limit (outer ergosurface), depending on the BH spin-mass ratio and the fluid initial momentum only. The turning corona for jet-like-flow has larger thickness, it is separated from the torus flow turning corona and it is closer to the BH stationary limit. Turning points of matter accreting from torus and from jets are independent explicitly of the details of the accretion and tori model. The turning corona could be observable due to an increase of flow luminosity and temperature. The corona is larger on the BH equatorial plane, where it is the farthest from the central attractor, and narrower on the BH poles.