Discovery of High-Frequency Quasi-periodic Oscillations in the Black Hole Candidate XTE J1859+226
Abstract
We report the discovery of quasi-periodic oscillations (QPOs) at roughly 187 and 150 Hz in the X-ray intensity of X-ray nova XTE J1859+226. The source was observed during a recent outburst with the Rossi X-Ray Timing Explorer. Besides these high-frequency QPOs, we have also detected QPOs (and sometimes their harmonics) at 6-7 Hz and significant broadband variability at low frequencies. These properties, as well as the observed hard X-ray spectrum, make XTE J1859+226 a black hole candidate (BHC). The detection of QPOs at two distinct frequencies >~100 Hz in two observations separated by about 4 hr provide additional insights into the high-frequency QPO phenomenon in BHCs. The importance lies in the proposed interpretations, which invariably involve the effects of strong gravity near a black hole. We compare our results to those of other BHCs and discuss the impact of the observational data on the models in a global context.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2000
- DOI:
- 10.1086/312712
- Bibcode:
- 2000ApJ...535L.123C
- Keywords:
-
- Stars: Binaries: General;
- Relativity;
- Stars: Individual: Alphanumeric: XTE J1859+226;
- Stars: Oscillations;
- X-Rays: Stars