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Anti-correlated hard X-ray time lags in Galactic black hole sources

K. Sriram·V. K. Agrawal·Jayant K. Pendharkar·A. R. Rao
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Abstract

We investigate the accretion disk geometry in Galactic black hole sources by measuring the time delay between soft and hard X-ray emissions. Similar to the recent discoveries of anti-correlated hard X-ray time lags in Cyg X-3 and GRS 1915+105, we find that the hard X-rays are anti-correlated with soft X-rays with a significant lag in another source: XTE J1550-564. We also find the existence of pivoting in the model independent X-ray spectrum during these observations. We investigate time-resolved X-ray spectral parameters and find that the variation in these parameters is consistent with the idea of a truncated accretion disk. The QPO frequency, which is a measure of the size of truncated accretion disk, too changes indicating that the geometric size of the hard X-ray emitting region changes along with the spectral pivoting and soft X-ray flux. Similar kind of delay is also noticed in 4U 1630-47.

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K. Sriram, V. K. Agrawal, Jayant K. Pendharkar, A. R. Rao. 2007-03-05. Anti-correlated hard X-ray time lags in Galactic black hole sources. https://doi.org/10.1086/516771

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