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Using the Chandra X-ray Observatory and the Rossi X-ray Timing Explorer, wehave studied the black hole candidate (BHC) X-ray transient XTE J1650-500 nearthe end of its 2001-2002 outburst after its transition to the low-hard state atX-ray luminosities down to L = 1.5E34 erg/s (1-9 keV, assuming a sourcedistance of 4 kpc). Our results include a characterization of the spectral andtiming properties. At the lowest sampled luminosity, we used an 18 ks Chandraobservation to measure the power spectrum at low frequencies. For the 3 epochsat which we obtained Chandra/RXTE observations, the 0.5-20 keV energy spectrumis consistent with a spectral model consisting of a power-law with interstellarabsorption. We detect evolution in the power-law photon index from 1.66 +/-0.05 to 1.93 +/- 0.13 (90% confidence errors), indicating that the sourcesoftens at low luminosities. The power spectra are characterized by strong(20-35% fractional rms) band-limited noise, which we model as a zero-centeredLorentzian. Including results from an RXTE study of XTE J1650-500 near thetransition to the low-hard state by Kalemci et al. (2003), the half-width ofthe zero-centered Lorentzian (roughly where the band-limited noise cuts off)drops from 4 Hz at L = 7E36 erg/s (1-9 keV, absorbed) to 0.067 +/- 0.007 Hz atL = 9E34 erg/s to 0.0035 +/- 0.0010 Hz at the lowest luminosity. While thespectral and timing parameters evolve with luminosity, it is notable that thegeneral shapes of the energy and power spectra remain the same, indicating thatthe source stays in the low-hard state. This implies that the X-ray emittingregion of the system likely keeps the same overall structure, while theluminosity changes by a factor of 470. We discuss how these results mayconstrain theoretical black hole accretion models.Comment: 11 pages, accepted by ApJ after minor revision

Detection of Low‐Hard State Spectral and Timing Signatures from the Black Hole X‐Ray Transient XTE J1650−500 at Low X‐Ray Luminosities