Global Operation of Resistive, Radiation-Inefficient, Accretion Flows in Preparing Jet-Driving Circumstances

TL;DR

This paper develops a global resistive RIAF model that accurately describes the magnetic and energetic conditions in accretion disks, elucidating the power transfer mechanisms that drive astrophysical jets.

Contribution

It presents a more precise global solution for resistive RIAFs, clarifying the energy transfer from outer disk regions to jet-launching inner regions.

Findings

Electrodynamic power is transported inward via Poynting flux.

The injected electromagnetic power exceeds local fluid work.

The model is exact in both large and small radius limits.

Abstract

In our recent paper, we have obtained a model solution to the problem of radiation-inefficient accretion flows (RIAFs) in a global magnetic field (so called, resistive RIAF model), which is asymptotically exact in outer regions of such flows forming accretion disks. When extrapolated inwardly, the model predicts a local enhancement of the vertical Poynting flux within a small radius that may be regarded as the disk inner-edge. This fact has been interpreted as the origin of power source for the astrophysical jets observationally well-known to be ejected from this type of accretion disks. Since the accuracy of the solution may become rather poor in such inner regions, however, the ground of this assertion may not seem to be so firm. In the present paper, we develop a sophisticated discussion for the appearance of jet-driving circumstances, based on a much more firm ground by deriving a global solution in the same situation. Although the new solution still has an approximate nature, it becomes exact in the limits not only of large radius but also of small radius. The analytic results clarify that the electrodynamic power is gathered by the Poynting flux, from outer main-disk region to feed the innermost part of an accretion disk. The injected power largely exceeds the local supply of work by the fluid motion.