Probing the Accretion-flow Dynamics using an Energy Dependent Timing Analysis in Black Hole X-ray Binaries
Abstract
I present a timing study of the black hole X-ray binary (BHB) SWIFT J1753.5-012, which for the first time uses the Swift X-Ray Telescope (XRT) to measure the energy dependence of all power spectral components. The soft (< 2 keV) and hard (> 2 keV) band show dramatically different behavior, suggesting that the hot flow is more variable in the peak of the outburst and the disk is more variable at low intensities. This result is important in understanding the role of the disk in the origin of the variability and how it stabilizes in (and towards) the high state when the source shows very little (or no) variability. I will also discuss ongoing XRT work on two more BHBs (MAXI J1659-152 and GX 339-4) one result of which is that the low frequency (< 10 Hz) Quasi Periodic Oscillation (QPO) is more coherent in the hard band than in the soft band, and the strong implications this has for our understanding of the geometry of the accretion flow that provides the driving mechanism (Lense-Thirring precession of the hot inner flow). Swift XRT timing study is making an important contribution to understanding accretion onto black holes as it allows us to probe the energies below 2 keV which were inaccessible to the Rossi X-ray Timing Explorer, but timing with the XRT has some issues and potential pitfalls that I shall briefly address.
- Publication:
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AAS/High Energy Astrophysics Division #13
- Pub Date:
- April 2013
- Bibcode:
- 2013HEAD...1312642K