2001MNRAS.320..316N -
Mon. Not. R. Astron. Soc., 320, 316-326 (2001/January-3)
A good long look at the black hole candidates LMC X-1 and LMC X-3.
NOWAK M.A., WILMS J., HEINDL W.A., POTTSCHMIDT K., DOVE J.B. and BEGELMAN M.C.
Abstract (from CDS):
LMC X-1 and LMC X-3 are the only known persistent stellar-mass black-hole candidates that have almost always shown spectra that are dominated by a soft, thermal component. We present here results from 170-ks-long Rossi X-ray Timing Explorer (RXTE) observations of these objects, taken in 1996 December, where their spectra can be described by a disc blackbody plus an additional soft {formmu1} high-energy power law (detected up to energies of 50keV in LMC X-3). These observations, as well as archival Advanced Satellite for Cosmology and Astrophysics (ASCA) observations, constrain any narrow Fe line present in the spectra to have an equivalent width ≲90eV. Stronger, broad lines (~150eV EW, {formmu2} are permitted. We also study the variability of LMC X-1. Its X-ray power spectral density (PSD) is approximately proportional to {formmu3} between 10–3 and 0.3Hz with a root-mean-square (rms) variability of ~7per cent. At energies >5keV, the PSD shows evidence of a break at {formmu4} possibly indicating an outer disc radius of ≲1000GMc2 in this likely wind-fed system. Furthermore, the coherence function {formmu5} a measure of the degree of linear correlation between variability in the >5keV band and variability in the lower energy bands, is extremely low (≲50per cent). We discuss the implications of these observations for the mechanisms that might be producing the soft and hard X-rays in these systems.
Abstract Copyright:
Blackwell Science Ltd
Journal keyword(s):
accretion, accretion discs - black hole physics - binaries: spectroscopic - stars: individual: LMC X-1 - stars: individual: LMC X-3 - X-rays: stars
Simbad objects:
5
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