Energy Spectra and High-Frequency Oscillations in 4U 0614+091
Abstract
We investigate the behavior of the high-frequency quasi-periodic oscillations (QPOs) in 4U 0614+091, combining timing and spectral analyses of RXTE observations. The energy spectra of the source can be described by a power law (α ~ 2.8) and a blackbody (kT ~ 1.5 keV), with the blackbody accounting for 10%-20% of the total energy flux. We find a robust correlation of the frequency, ν, of the higher frequency QPO near 1 kHz with the flux of the blackbody, FBB. The slope of this correlation, d log ν/d log FBB, is 0.27-0.37. The source follows the same relation even in observations separated by several months. The QPO frequency does not have a similarly unique correlation with the total flux or the flux of the power-law component. The rms fraction of the higher frequency QPO rises with energy from 6.8% +/- 1.5% (3-5 keV) to 21.3% +/- 4.0% (10-12 keV). For the lower frequency QPO, however, it is consistent with a constant value of 5.4% +/- 0.9%. The results may be interpreted in terms of a beat-frequency model for the production of the high-frequency QPOs.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- September 1997
- DOI:
- 10.1086/310827
- arXiv:
- arXiv:astro-ph/9706100
- Bibcode:
- 1997ApJ...486L..47F
- Keywords:
-
- ACCRETION;
- ACCRETION DISKS;
- STARS: INDIVIDUAL ALPHANUMERIC: 4U 0614+091;
- STARS: NEUTRON;
- X-RAYS: STARS;
- Accretion;
- Accretion Disks;
- Stars: Individual: Alphanumeric: 4U 0614+091;
- Stars: Neutron;
- X-Rays: Stars;
- Astrophysics
- E-Print:
- 9 pages, 3 figures, submitted to ApJL, for more information on this and other QPO papers see http://www.astro.columbia.edu/~eric/qpos.html