Magnetically-Dominated Accretion Flows (MDAFs) and Jet Production in the Low/Hard STate

Abstract

In this paper I propose that the inner part of a black hole accretion inflow ($< 100 r_{g}$) may enter a magnetically-dominated, magnetosphere-like phase in which the strong, well-ordered fields play a more important role than weak, turbulent fields. In the low/hard state this flow is interior to the standard ADAF usually invoked to explain the observed hot, optically thin emission. Preliminary solutions for these new MDAFs are presented. Time-dependent X-ray and radio observations give considerable insight into these processes, and a new interpretation of the X-ray power spectrum (as arising from many disk radii) may be in order. While an evaporative ADAF model explains the noise power above 0.01 Hz, an inner MDAF is needed to explain the high frequency cutoff near 1 Hz, the presence of a QPO, and the production of a jet. The MDAF scenario also is consistent with the data-based, phemonenological models presented at this meeting by several authors.