A unified accretion-ejection paradigm for black hole X-ray binaries

Abstract

Context. We proposed in paper I that the spectral evolution of transient X-ray binaries (XrB) is due to an interplay between two flows: a standard accretion disk (SAD) in the outer parts and a jet-emitting disk (JED) in the inner parts. We showed in papers II, III, and IV that the spectral evolution in X-ray and radio during the 2010–2011 outburst of GX 339-4 can be recovered. However, the observed variability in X-ray was never addressed in this framework. Aims. We investigate the presence of low frequency quasi-periodic oscillations (LFQPOs) during an X-ray outburst, and address the possible correlation between the frequencies of these LFQPOs and the transition radius between the two flows, rJ. Methods. We select X-ray and radio data that correspond to 3 outbursts of GX 339-4. We use the method detailed in Paper IV to obtain the best parameters rJ(t) and ṁin(t) for each outburst. We also independently search for X-ray QPOs in each selected spectra and compare the QPO frequency to the Kepler and epicyclic frequencies of the flow in rJ. Results. We successfully reproduce the correlated evolution of the X-ray spectra and the radio emission for 3 different activity cycles of GX 339-4. We use a unique normalisation factor for the radio emission, f∼R. We also report the detection of 7 new LFQPOs (3 Type B, and 4 Type C), to go along with the ones previously reported in the literature. We show that the frequency of Type C QPOs can be linked to the dynamical JED-SAD transition radius rJ, rather than to the optically thin-thick transition radius in the disk. The scaling factor q such that νQPO ≃ νK(rJ)/q is q ≃ 70 − 130, a factor consistent during the 4 cycles, and similar to previous studies. Conclusions. The JED-SAD hybrid disk configuration not only provides a successful paradigm allowing us to describe XrB cycles, but also matches the evolution of QPO frequencies. Type C QPOs provide an indirect way to probe the JED-SAD transition radius, where an undetermined process produces secular variability. The demonstrated relation between the transition radius links Type C QPOs to the transition between two different flows, effectively tying it to the inner magnetized structure, i.e., the jets. This direct connection between the jets’ (accretion-ejection) structure and the process responsible for Type C QPOs, if confirmed, could naturally explain their puzzling multi-wavelength behavior.

Tracking the evolution of the accretion flow in MAXI J1820+070 during its hard state with the JED-SAD model

“…reflection dominates over the direct JED emission. While this is slightly different with respect to the results obtained by Marcel et al (2019Marcel et al ( , 2020, it is noteworthy that these authors did not have data above 40 keV and, most importantly, they did not directly perform spectral fits on the data. In future applications of the JED-SAD model, the inclusion of high energy NuSTAR and especially BAT data might therefore be necessary to highlight the role, if any, of m S in shaping the spectra of BHTs in hard state and, particularly, their high energy cutoff.…”

“…Finally, it has been recently shown that also some timing features could be explained within the JED-SAD paradigm framework. Indeed, a direct proportionality has been observed between the Keplerian frequency of the transition radius R J and the type-C QPO frequency in four different outbursts of GX 339−4 (Marcel et al 2020). According to these results, this type of QPOs could originate at the interface between two regions of different values of µ, i.e.…”

“…A detailed description of the model has been presented in Marcel et al (2018b,a) and we refer the reader to these papers for more details. This spectral model has been successfully used to reproduce the X-ray spectral evolution of the BHT GX 339−4 during four outbursts between 2001 and 2011 (Marcel et al 2019(Marcel et al , 2020. Moreover, using the R J − Ṁin pairs that best described the X-ray spectra in a hard state, these authors were also able to reproduce the jet emission observed simultaneously in the radio band.…”

“…However, in none of these updated versions of the model the correlation between accretion flow and jets has been addressed. An attempt to connect accretion and ejection in a unified model has been recently reported in a number of papers (Ferreira et al 2006;Marcel et al 2018bMarcel et al ,a, 2019Marcel et al , 2020. This model connects the spectral evolution BHTs in outbursts to changes in the multiflow configuration of the accretion disk, similarly to the approach of e.g., Esin et al (1997).…”

Expected evolution of disk wind properties along an X-ray binary outburst

“…The vertical dashed line corresponds to the MJD reported in Table 1. discussed in detail in Marcel et al (2019) (the three other outbursts of this source during the RXTE era have been analyzed in Marcel et al 2020). We have reported the comparison between the observations and the model in Fig.…”