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Temporal and Spectral Correlations of Cyg X-1

T. P. Li·Y. X. Feng·L. Chen
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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.

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T. P. Li, Y. X. Feng, L. Chen. 1999-03-16. Temporal and Spectral Correlations of Cyg X-1. https://doi.org/10.1086/307566

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