Bibcode
Gandhi, P.; Dhillon, V. S.; Durant, M.; Fabian, A. C.; Makishima, K.; Marsh, T. R.; Miller, J. M.; Shahbaz, T.; Spruit, H. C.
Bibliographical reference
X-RAY ASTRONOMY 2009; PRESENT STATUS, MULTI-WAVELENGTH APPROACH AND FUTURE PERSPECTIVES: Proceedings of the International Conference. AIP Conference Proceedings, Volume 1248, pp. 119-122 (2010).
Advertised on:
7
2010
Citations
0
Refereed citations
0
Description
In a fast multi-wavelength timing study of black hole X-ray binaries
(BHBs), we have discovered correlated optical and X-ray variability in
the low/hard state of two sources: GX 339-4 and SWIFT J1753.5-0127.
After XTE J1118+480, these are the only BHBs currently known to show
rapid (sub-second) aperiodic optical flickering. Our simultaneous
VLT/Ultracam and RXTE data reveal intriguing patterns with
characteristic peaks, dips and lags down to very short timescales.
Simple linear reprocessing models can be ruled out as the origin of the
rapid, aperiodic optical power in both sources. A magnetic energy
release model with fast interactions between the disk, jet and corona
can explain the complex correlation patterns. We also show that in both
the optical and X-ray light curves, the absolute source variability
r.m.s. amplitude linearly increases with flux, and that the flares have
a log-normal distribution. The implication is that variability at both
wavelengths is not due to local fluctuations alone, but rather arises as
a result of coupling of perturbations over a wide range of radii and
timescales. These `optical and X-ray rms-flux relations' thus provide
new constraints to connect the outer and inner parts of the accretion
flow, and the jet.