Seminars

"A unified accretion ejection paradigm for X-ray binaries: the JED-SAD paradigm"

Grégoire Marcel (University of Cambridge)

The hysteresis behavior of X-ray binaries during their outbursts remains a mystery. In this work, we developed a paradigm where the disk material accretes in two possible, mutually exclusive, ways (Ferreira et al. 2006). In the usual alpha-disk mode (SAD, Shakura & Sunayev 1973), the dominant local torque is due to a radial transport of the disk angular momentum. In the jet-emitting disk mode (JED), magnetically-driven jets carry away mass, energy, and angular momentum vertically. Within this framework, the transition from one mode to another is related to the magnetic field distribution, an unknown. We have shown that typical hard states of X-ray binaries can be reproduced up to unprecedented X-ray luminosities in this paradigm (Marcel et al. 2018a,b,2019). Direct spectral fits have since been performed on an AGN (Ursini et al,. 2020), as well as two X-ray binaries (Marino et al. 2021, Barnier et al. 2022), showing striking dynamical similarities between the two accretion flow structures despite the factor > 10^6 in mass. Moreover, we have addressed the production of low frequency quasi-periodic oscillations during the outbursts (Marcel et al. 2020, Marcel & Neilsen 2021), the radiative efficiency of the accretion flow and the associated radio--X-ray correlation (Marcel et al. 2022), as well as the production of winds (Petrucci et al. 2021), the latest results from IXPE (Zhang et al., in prep.), and the timing properties of X-ray binaries (Malzac & Marcel, to be submitted).