Disk-jet-wind coupling from stellar mass to supermassive black holes

TL;DR

This work surveys a unified disk–jet–wind framework that connects accretion states from stellar-mass to supermassive black holes, emphasizing a spectral transition at $\dot{m}=L/L_{\rm Edd}\sim 0.01$ from a cool, thin disc to a hot, radiatively inefficient flow. It argues that jets are driven by the hot flow and winds by X-ray irradiation, with the radio–X-ray fundamental plane arising when jet power scales with accretion power and X-ray emission originates from an ADAF; spin and net magnetic flux (MAD vs SANE) provide the primary modulation of jet power, especially for radio-loud objects. The picture is challenged by bright hard states, inner-disc/reflection/polarimetry constraints on corona geometry, and theoretical uncertainties in heating prescriptions and MAD/SANE dynamics. Extending to AGN, the same transitions and jet–wind linkages appear, but disc temperatures and DIM applicability differ, requiring consideration of environmental effects and spin/magnetic flux as additional controls on jet power. Overall, the paper advocates a parsimonious, spin-and-flux–driven extension of the fundamental plane to unify disk–jet–wind physics across the black hole mass scale, while acknowledging unresolved issues in corona geometry and transition mechanisms.

Abstract

Black holes are the simplest possible objects, characterised by only mass and spin. We see them via accretion, so there is one more fundamental parameter which is the mass accretion rate. Here I will review how the data from both stellar and supermassive black holes can be fit into a framework where there is a major spectral transition at $\dot{m}=L/L_{\rm Edd}\sim 0.01$ where the optically thick disc is replaced by a hot flow. This dramatic spectral change also affects the expected properties of thermal and radiatively powered winds, matching the overall properties of winds seen in new XRISM data from the stellar mass binaries, though there can also be additional UV and dust driven winds in supermassive black holes. The radio data in stellar and supermassive black holes are clear that the hot flow (not the disc) connects to the radio jet, and the radio-X-ray 'fundamental plane' can be qualitatively understood if the radio quiet AGN and stellar mass black holes have low to moderate spins, with the jet power set as a constant fraction of the accretion power. A small fraction of AGN (radio loud) instead have much higher (factor $100-1000\times$) radio-to-X-ray ratio at the same black hole mass and mass accretion rates. I speculate that these have higher jet power due to high black hole spin. I review the multiple issues still remaining in this picture, most of which are connected to the geometry and nature of the X-ray corona, and the conflicting constraints on this which come from reflection spectroscopy and polarimetry.

Figures (1)

• Figure 1: Fundamental plane from stellar mass black holesBahramian2022 with "radio loud" in red (almost all of the original sample in Merloni2003), "radio quiet" in yellow. These are actually within an order of magnitude of each other. Instead, the stars show the stacked non-detected in radio (VLASS) AGN sample in three mass accretion rate bins (blue: $L/L_{\rm Edd}\sim 0.01$, orange: $L/L_{\rm Edd}\sim 0.02$, green: $L/L_{\rm Edd}\sim 0.07$) are all slightly below the extrapolated relation from all the stellar mass black holes. This contrasts with the few individually detected VLASS radio sources (faint: diamonds, middle: hexagons, bright: circles). The inset shows a zoom-in of the AGN. These have a factor 100-1000$\times$ larger radio flux for the same range of mass and mass accretion rate and large scale environment as the stacked non-deteced AGN. Clearly there is another parameter in addition to mass and mass accretion rate which controls the jet power Kang2025b.