Long-term X-ray variability of Swift J1644+57
MetadataShow full item record
We studied the X-ray timing and spectral variability of the X-ray source Sw J1644+57, a candidate for a tidal disruption event. We have separated the long-term trend (an initial decline followed by a plateau) from the short-term dips in the Swift light curve. Power spectra and Lomb–Scargle periodograms hint at possible periodic modulation. By using structure function analysis, we have shown that the dips were not random but occurred preferentially at time intervals ≈(2.3, 4.5, 9) × 105 s and their higher order multiples. After the plateau epoch, dipping resumed at ≈(0.7, 1.4) × 106 s and their multiples. We have also found that the X-ray spectrum became much softer during each of the early dips, while the spectrum outside the dips became mildly harder in its long-term evolution. We propose that the jet in the system undergoes precession and nutation, which causes the collimated core of the jet briefly to go out of our line of sight. The combined effects of precession and nutation provide a natural explanation for the peculiar patterns of the dips. We interpret the slow hardening of the baseline flux as a transition from an extended, optically thin emission region to a compact, more opaque emission core at the base of the jet.
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society, ©: 2012, the authors and the Royal Astronomical Society. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.
Showing items related by title, author, creator and subject.
Blustin, A.; Dwelly, T.; Page, M.; McHardy, I.; Seymour, Nick; Kennea, J.; Loaring, N.; Mason, K.; Sekiguchi, K. (2008)Broad absorption-line quasars (commonly termed BALQSOs) contain the most dramatic examples of active galactic nucleus (AGN) driven winds. The high absorbing columns in these winds, ~1024 cm-2, ensure that BALQSOs are ...
Uemura, Makoto; Kato, Taichi; Ishioka, Ryoko; Tanabe, Kenji; Torii, Ken; Santallo, Roland; Monard, Berto; Markwardt, Craig; Swank, Jean; Sault, Robert; Macquart, Jean-Pierre; Linnolt, Michael; Kiyoto, Seiichiro; Stubbings, Rod; Nelson, Peter; Richards, Tom; Bailyn, Charles; West, Doug; Masi, Gianluca; Miyashita, Atsushi; Sano, Yasuo; Scarmato, Toni (2003)The black hole X-ray binary V4641 Sgr experienced an outburst in 2002 May, which was detected at X-ray, optical, and radio wavelengths. The outburst lasted for only 6 days, but the object remained active for the next ...
A statistical comparison of the optical/UV and X-ray afterglows of gamma-ray bursts using the Swift Ultraviolet Optical and X-ray TelescopesOates, S.; Page, M.; Schady, P.; De Pasqualea, M.; Evans, P.; Page, K.; Chester, M.; Curran, Peter; Koch, T.; Kuin, N.; Roming, P.; Siegel, M.; Zane, S.; Nousek, J. (2011)We present the systematic analysis of the Ultraviolet/Optical Telescope (UVOT) and X-ray Telescope (XRT) light curves for a sample of 26 Swift gamma-ray bursts (GRBs). By comparing the optical/UV and X-ray light curves, ...