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[31.13] Spectral and Timing Properties of the Low/Hard States in LMC X-3

P. T. Boyd (JCA/UMBC and LHEA/GSFC), A. P. Smale (USRA and LHEA/GSFC), J. Homan, M. van der Klis, P. G. Jonker (Amsterdam), E. Kuulkers (SRON, Utrecht), J. Wilms (IAA/Tuebingen), M. Nowak (JILA)

Three RXTE PCA observations of LMC X-3 were obtained on 2000 May 3, 10 and 13 when the black-hole candidate binary was in an extended episode of low soft X-ray flux. Spectral analysis of the observations confirms that LMC X-3 exhibits recurrent low/hard states as discovered by Wilms et al. (2000). The data are fit well by a pure power law with photon index Gamma = 1.69 +/- 0.02 with a source luminosity at 50 kpc of 5-16 x 10³⁶ erg/s (2-10 keV). Timing analysis reveals strong broad-band variability with fractional rms amplitude 40 +/4 % and the discovery of a QPO centered at 0.46 +/- 0.02 Hz and rms amplitude of 14 %. This is the first reported QPO in LMC X-3. We reanalyze several archival RXTE observations of LMC X-3, deriving consistent spectral and timing parameters, and determining the overall luminosity variation between high and low states. The timing and spectral properties are found to be quantitatively similar to those of galactic black hole candidates.