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$\begin{figure} \par\includegraphics[width=13.5cm,clip]{2689fig1.epsf}\end{figure}$ Figure 1: A Standard Accretion Disc (SAD) is established down to a radius r_J which marks the transition towards a low radiative Jet Emitting Disc (JED), settled down to the last stable orbit. The JED is driving a mildly relativistic, self-collimated electron-proton jet which, when suitable conditions are met, is confining an inner ultra-relativistic electron-positron beam. The MHD power $P_{\rm MHD}$ flowing from the JED acts as a reservoir for (1) heating the jet basis (radiating as a moving thermal corona with power $P_{\rm c}$ ); (2) heating the inner pair beam ( $P_{\rm e^+e^-}$ ) and (3) driving the compact jet ( $P_{\rm jet}$ ). Field lines are drawn in solid lines and the number density is shown in greyscale ( $\log_{10} n/\mbox{m}^{-3}$ ). The MAES solution (JED and MHD jet) was computed with $\xi =0.01$ , $\varepsilon =0.01$ and with m=10 and $\dot m(r_J)=0.01$ (see text).
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In the text

$\begin{figure} \par\includegraphics[width=11cm,clip]{2689fig2.ps}\end{figure}$ Figure 2: The canonical spectral states of BH X-ray binaries. a) Quiescent state obtained with a low $\dot m$ and a large r_J: the Jet Emitting Disc (JED) occupies a large zone in the accretion disc. b) Hard state with much larger $\dot m$ and smaller r_J: the pair creation threshold is still not reached. c) Soft state when $\dot m$ is such that there is no zone anymore within the disc where an equipartition field is present: no JED, hence neither MHD jet nor pair beam. d) Luminous Intermediate state between the Hard and the Soft states: the high disc luminosity (SAD) combined with the presence of a MHD jet allows pair creation and acceleration along the axis, giving birth to flares and superluminal ejection events.
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In the text