Anticorrelated 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 anticorrelated hard X-ray time lags in Cygnus X-3 and GRS 1915+105, we find that the hard X-rays are anticorrelated 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 disks, also changes, indicating that the geometric size of the hard X-ray emitting region changes along with the spectral pivoting and soft X-ray flux. A similar kind of delay is also noticed in 4U 1630-47.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2007
- DOI:
- 10.1086/516771
- arXiv:
- arXiv:astro-ph/0703074
- Bibcode:
- 2007ApJ...661.1055S
- Keywords:
-
- Accretion;
- Accretion Disks;
- Stars: Binaries: Close;
- Stars: Individual: Alphanumeric: XTE J1550-564;
- Stars: Individual: Alphanumeric: 4U 1630-47;
- X-Rays: Binaries;
- Astrophysics
- E-Print:
- 14 pages, 7 figures, accepted for publication in ApJ