Discovery of Two Simultaneous Kilohertz Quasi-periodic Oscillations in the Persistent Flux of GX 349+2
Abstract
We report the discovery of two simultaneous quasi-periodic oscillations in the persistent flux of GX 349+2 at frequencies 712+/-9 and 978+/-9 Hz, with rms amplitudes 1.25%+/-0.34% and 1.34%+/-0.32%, respectively. During our 152 ks observation with the Rossi X-ray Timing Explorer, GX 342+2 was in either the normal branch or the flaring branch with count rates in the nominal 2-60 keV RXTE-PCA band ranging from a low of 8000 counts s-1 to a high of 15,000 counts s-1. The kHz QPOs were observed only when the source was at the top of the normal branch, when the count rate was about 8200 counts s-1, corresponding to a flux of 1.4×10-8 ergs cm-1 s-1 in the 2-10 keV band. With this report, now kHz QPOs have been observed in all six Z sources.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1998
- DOI:
- 10.1086/311423
- arXiv:
- arXiv:astro-ph/9804225
- Bibcode:
- 1998ApJ...500L.167Z
- Keywords:
-
- ACCRETION;
- ACCRETION DISKS;
- STARS: NEUTRON;
- STARS: INDIVIDUAL ALPHANUMERIC: GX 349+2;
- X-RAYS: STARS;
- Accretion;
- Accretion Disks;
- Stars: Individual: Alphanumeric: GX 349+2;
- Stars: Neutron;
- X-Rays: Stars;
- Astrophysics
- E-Print:
- 5 pages, LaTex (aas2pp4), Accepted for publication in ApJ Lett