SIMBAD references

We present a framework for understanding the dynamical and spectral properties of X-ray binaries, where the presence of an organized large-scale magnetic field plays a major role. Such a field is threading the whole accretion disc with an amplitude measured by the disc magnetization µ(r, t) = B²_z/(µ_oP_tot), where P_tot is the total, gas and radiation, pressure. Below a transition radius r_J, a jet emitting disc (JED) is settled and drives self-collimated non-relativistic jets. Beyond r_J, no jet is produced despite the presence of the magnetic field and a standard accretion disc (SAD) is established. The radial distribution of the disc magnetization µ adjusts itself to any change in the disc accretion rate, thereby modifying the transition radius r_J.

We propose that a SAD-to-JED transition occurs locally, at a given radius, in a SAD when µ = µ_max≃ 1 while the reverse transition occurs in a JED only when µ = µ_min≃ 0.1. This bimodal behaviour of the accretion disc provides a promising way to explain the hysteresis cycles followed by X-ray binaries during outbursts.