The multi-wavelength emission of X-ray binary jets powered by internal shock
Abstract
The emission of steady compact jets observed in the hard spectral state of X-ray binaries and in AGN is likely to be powered by internal shocks caused by fluctuations of the outflow velocity. Those fluctuations are likely to originate in the accretion flow. Using the internal shock model ishem, I explore this possible connection between accretion and ejection. The fluctuations of the accretion flow can in principle be traced by the X-ray light curves, while the response of the synchrotron jet can be observed with radio and IR measurements. Under the assumption that the power spectrum of the jet fluctuations is identical to that of the observed X-ray light curve, we calculate the predictions of the model and make comparisons to spectral and timing data from several X-ray binaries. The we find that in GX 339-4 and MAXI J1836- 194 the model provides a good description of the observed radio optical SEDs. In the case of MAXI J1836-192 we model the evolution of the SED in the hard state during an outburst. Our results indicate that in this source, not only the jet power but also the jet time averaged Lorentz factor increases with luminosity. We also find that the quenching of the jet in the soft state might be related to the drop in X-ray variability: the jet could be present in the soft state but undetected due to a very low radiative efficiency associated to very weak velocity fluctuations. The model also predicts a strong, wavelength dependent jet variability that resembles the observed one. In particular, strong sub-second variability is predicted in the infrared and optical bands. In the cas of GX 339-4 complex timing correlations are observed between the IR/optical light curves and the X-rays that we use to probe the fast dynamics of the accretion/ejection connection. In this source also low frequency QPOs have been detected simultaneously in X-ray and IR. The appearance of the IR QPO could be caused by jet precession driven by Lense-Thirring precession of the X-ray accretion flow.
- Publication:
-
42nd COSPAR Scientific Assembly
- Pub Date:
- July 2018
- Bibcode:
- 2018cosp...42E2150M