A unified accretion–ejection paradigm for Black Hole X-ray binaries

• Published in: Advances in space research 2006, Vol.38 (12), p.2909-2911
• Main Authors: Petrucci, P.O., Ferreira, J., Henri, G., Sauge, L., Pelletier, G.
• Format: Article
• Language: English
• Subjects: Accretion; Jets; Microquasars; Multiwavelength
• ISSN: 0273-1177; 1879-1948
• DOI: 10.1016/j.asr.2006.02.069

We present a unified accretion–ejection picture that explains the different spectral state of Black Hole X-ray binaries (BHXrB) from radio to X/γ-rays. In this view, the central region of BHXrB has a multi-flow configuration which consists in (1) an outer standard accretion disc, (2) an inner magnetized accretion disc driving, (3) a self-collimated electron–proton MHD jet, surrounding and (4) a relativistic electron–positron beam when adequate conditions are met. This picture provides a simple and unified explanation to the various canonical spectral states of BH X-ray binaries, by varying the transition radius r J between the inner disc driving jets and the outer standard disc. In this framework, large r J correspond to Quiescent and Hard states while small r J correspond to Thermal Dominant ones. In between these two extremes, r J can reach values that switches on the pair cascade process giving birth to a relativistic electron–positron beam. This would correspond to the bright intermediate state.