2000ApJ...542L.127B

We present results from three observations with the Rossi X-Ray Timing Explorer (RXTE) of LMC X-3, obtained while the source was in an extended low/hard state. The data reveal a hard X-ray spectrum that is well fit by a pure power law with photon index Γ=1.69±0.02, with a source luminosity at 50 kpc of (5-16)x10³⁶ ergs.s^–1 (2-10 keV). Strong broadband (0.01-100 Hz) time variability is also observed, with fractional rms amplitude 40%±4%, plus a quasi-periodic oscillation (QPO) peak at 0.46±0.02 Hz with rms amplitude ∼14%. This is the first reported observation in which the full canonical low/hard state behavior (pure hard power-law spectrum combined with strong broadband noise and QPO) for LMC X-3 is seen. We reanalyze several archival RXTE observations of LMC X-3, derive consistent spectral and timing parameters, and determine the overall luminosity variation between high/soft and low/hard states. The timing and spectral properties of LMC X-3 during the recurrent low/hard states are quantitatively similar to that typically seen in the Galactic black hole candidates.