The X-ray outburst of H1743-322 in 2003:: High-frequency QPOs with a 3:2 frequency ratio

The 2003 X- ray outburst of the candidate black hole binary, H1743 - 322, was investigated in frequent pointed observations ( 2 - 250 keV) with the Rossi X- Ray Timing Explorer ( RXTE). One particular program of 130 observations is organized into 111 time intervals and searched for the presence of high- frequency quasi- periodic oscillations ( HFQPOs) in the range 50 - 2000 Hz. Only a single observation ( 2003 June 13) yields a detection above 4 sigma. The central frequency of 239 +/- 4 Hz is consistent with the 240 Hz QPO reported for this source on 2003 May 28 ( Homan and coworkers). We group the observations in several different ways and compute average power- density spectra ( PDS) in a search for further evidence of HFQPOs. Significant results are found for two groups defined by the presence of low- frequency QPOs ( 0.1 - 20 Hz) and an absence of band- limited'' power continua. ( 1) The nine time intervals with the highest X- ray flux yield a QPO at 166 +/- 5 Hz. ( 4.1 sigma; 3 - 35 keV). ( 2) The group with lower X- ray flux ( 24 time intervals) produces a QPO at 242 +/- 3 Hz ( 6.0 sigma; 7 - 35 keV). The ratio of these two frequencies is 1: 46 +/- 0: 05. This finding is consistent with results obtained for three other black hole systems that exhibit commensurate HFQPOs in a 3: 2 ratio. Furthermore, the occurrence of H1743 - 322' s slower HFQPO at times of higher X- ray luminosity closely resembles the behavior of XTE J1550 - 564 and GRO J1655 - 40. We discuss our results in terms of resonance models that invoke frequencies set by general relativity.