X-Ray Temporal Properties of XTE J1650–500 during Outburst Decay

We investigated the temporal behavior of the new black hole transient XTE J1650-500 with the Rossi X-Ray Timing Explorer as the source made a transition to the low/hard state during the decay of the 2001 outburst. We find quasi-periodic oscillations in the 4-9 Hz range, enhanced time lags, and reduced coherence during the state transition. We also observe a shift in the peak frequency of the noise component with energy during the transition. The evolution of the power spectrum, as well as the lag and coherence behavior during the state transition, are similar to the state transitions observed for other black hole sources, especially Cyg X-1. We suggest a possible geometry and evolution of a jet + corona + disk system, based on enhanced lags and peak frequency shift during the transition.