Temporal and Spectral Correlations of Cyg X-1

Abstract

Temporal and spectral properties of X-ray rapid variability of Cyg X-1 are studied by an approach of correlation analysis in the time domain on different time scales. The correlation coefficients between the total intensity in 2-60 keV and the hardness ratio of 13-60 keV to 2-6 keV band on the time scale of about 1 ms are always negative in all states. For soft states, the correlation coefficients are positive on all the time scales from about 0.01 s to 100 s, which is significantly different with that for transition and low states. Temporal structures in high energy band are narrower than that in low energy band in quite a few cases. The delay of high energy photons relative to low energy ones in the X-ray variations has also been revealed by the correlation analysis. The implication of observed temporal and spectral characteristics to the production region and mechanism of Cyg X-1 X-ray variations is discussed.

17 pages, 6 figures included, to appear in ApJ

References in corpus (9)

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• Understanding Spectral Variability and Time Lags in Accreting Black Holes
• Timescale Analysis of Spectral Lags
• X-ray time lags from a pivoting power law in black holes
• Timing in the Time Domain: Cygnus X-1
• A Peculiar Flaring Episode of Cygnus X-1
• Probing the Inflow/Out-flow and Accretion Disk of Cyg X-1 in the High State with HETG/Chandra
• X-Ray Spectral Variability in Cygnus X-1
• Radiative Processes and Geometry of Spectral States of Black-Hole Binaries
• Temporal and Spectral Properties of Gamma-Ray Flashes
• Diagnostics of Neutron Star and Black Hole X-Ray Binaries with X-Ray Shot Widths
• X-Ray Spectral Variability in Initial Rise of XTE J1550-564
• Timescale Spectra in High Energy Astrophysics
• X-Ray Variability Coherence in the Time Domain