High-frequency Quasi-Periodic Oscillations from GRS 1915+105 in its C state
Abstract
We report the results of a systematic timing analysis of RXTE observations of GRS 1915+105 when the source was in its variability class theta, characterized by alternating soft and hard states on a time scale of a few hundred seconds. The aim was to examine the high-frequency part of the power spectrum in order to confirm the hecto-Hertz Quasi-Periodic Oscillations (QPO) previously reported from observations from mixed variability behaviours. During the hard intervals (corresponding to state C in the classification of Belloni et al., 2000, A&A, 35, 271), we find a significant QPO at a frequency of ~170 Hz, although much broader (Q~2) than previously reported. No other significant peak is observed at frequencies >30 Hz. A time-resolved spectral analysis of selected observations shows that the hard intervals from class theta show a stronger and steeper (Gamma=2.8-3.0) power-law component than hard intervals from other classes. We discuss these results in the framework of hecto-Hertz QPOs reported from GRS 1915+105 and other black-hole binaries.
Keywords
Cite
@article{arxiv.astro-ph/0603210,
title = {High-frequency Quasi-Periodic Oscillations from GRS 1915+105 in its C state},
author = {T. Belloni and P. Soleri and P. Casella and M. Mendez and S. Migliari},
journal= {arXiv preprint arXiv:astro-ph/0603210},
year = {2009}
}
Comments
7 pages, 8 figures, accepted for publication on MNRAS