High‐ and Low‐Frequency Quasi‐periodic Oscillations in the X‐Ray Light Curves of the Black Hole Transient H1743−322

We present a variability study of the black hole candidate and X-ray transient H1743-322 during its 2003-2004 outburst. We analyzed five Rossi X-Ray Timing Explorer observations that were performed as part of a multiwavelength campaign, as well as six observations from the early rise of the outburst. The source was observed in several black hole states and showed various types of X-ray variability, including high-frequency quasi-periodic oscillations (QPOs) at 240 and 160 Hz (i.e., with a 3:2 frequency ratio), several types of low-frequency QPOs, and strong variations on a timescale of a few hundred seconds. The discovery of high-frequency QPOs in H1743-322 supports predictions that these QPOs should be more easily observed in high inclination systems. In one of our observations a transition in count rate and color occurred, during which we were able to follow the smooth evolution of the low-frequency QPOs from type B to type A. We classify the X-ray observations and QPOs and briefly discuss the QPOs in terms of recently proposed models