The cross-correlation analysis in Z source GX 349+2

Abstract

Using all the observations from Rossi X-ray Timing Explorer for Z source GX 349+2, we systematically carry out cross-correlation analysis between its soft and hard X-ray light curves. During the observations from January 9 to January 29, 1998, GX 349+2 traced out the most extensive Z track on its hardness-intensity diagram, making a comprehensive study of cross-correlation on the track. The positive correlations and positively correlated time lags are detected throughout the Z track. Outside the Z track, anti-correlations and anti-correlated time lags are found, but the anti-correlated time lags are much longer than the positively correlated time lags, which might indicate different mechanisms for producing the two types of time lags. We argue that neither the short-term time lag models nor the truncated accretion disk model can account for the long-term time lags in neutron star low mass X-ray binaries (NS-LMXBs). We suggest that the extended accretion disk corona model could be an alternative model to explain the long-term time lags detected in NS-LMXBs.

24 pages, 5 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

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Cited by in corpus (4)

• Constraining the Coronal Heights and Readjustment Velocities Based on the Detection of a Few Hundred Seconds Delays in the Z Source GX 17+2
• Broadband spectro-temporal investigation of neutron star low-mass X-ray binary GX 349+2
• A study of the cross-correlation and time lag in black hole X-ray binary XTE J1859+226
• Investigating the coronal structure by studying time lags in the Atoll source 4U 1705-44 using AstroSat