2000/04/17 by Wei Cui, Cui, Wei, C. R. Shrader +5
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0004236
To appear in ApJ Letters
arxiv created 2000/04/17 · arxiv updated 2009/12/01
We report the discovery of quasi-periodic oscillations (QPOs) at roughly 187 Hz and 150 Hz in the X-ray intensity of X-ray nova XTE J1859+226. The source was observed during a recent outburst with RXTE. Besides these high-frequency QPOs, we have also detected QPOs (and sometimes their harmonics) at 6--7 Hz, and significant broad-band 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 \gtrsim 100 Hz in two observations separated by about 4 hours 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.