Anti-correlated hard X-ray time lags in Galactic black hole sources
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.
Cite
@article{arxiv.astro-ph/0703074,
title = {Anti-correlated hard X-ray time lags in Galactic black hole sources},
author = {K. Sriram and V. K. Agrawal and Jayant K. Pendharkar and A. R. Rao},
journal= {arXiv preprint arXiv:astro-ph/0703074},
year = {2011}
}
Comments
14 pages, 7 figures, accepted for publication in ApJ