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SUMMARY:The 'voice' of the accretion disc in black hole X-ray binaries - T
 ony Wilkinson\, University of Southampton
DTSTART:20090916T140000Z
DTEND:20090916T141500Z
UID:TALK19875@talks.cam.ac.uk
CONTACT:Alexander Blustin
DESCRIPTION:The accretion disc is a key component in the X-ray spectra of 
 black hole X-ray binaries\, but until now the disc has not made itself hea
 rd above the noise variations of the power-law continuum component on time
 -scales of seconds or less. At least within the soft states\, the disc app
 ears to be relatively stable on these short time-scales. Here\, I will pre
 sent evidence for accretion disc variability in the hard states of black h
 ole X-ray binaries. I will show how reflection signatures can be used to d
 isentangle intrinsic disc variations from the variable blackbody emission 
 due to heating by the power-law. Using this approach and including new dat
 a on GX 339-4 from XMM-Newton\, I will demonstrate that the disc shows int
 rinsic variations on time-scales of seconds\, corresponding to the low-fre
 quency Lorentzian seen in the power spectrum. This correspondence suggests
  that the disc itself produces this timing signature\, and hence connects 
 the disc to all other timing signatures whose frequencies correlate with t
 hat of the low-frequency Lorentzian. I will also describe possible links b
 etween the unstable disc and the production of jets in the hard states\, a
 nd discuss the energy-dependent time-lags associated with the intrinsic di
 sc variability\, which can constrain the radial drift time-scales in the i
 nner disc. 
LOCATION:Sackler Lecture Theatre\, IoA
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