XMM-Newton EPIC and RGS observations of LMC X-3

Abstract

We report the results of preliminary analysis of the {XMM-Newton} EPIC and RGS observations of the candidate black-hole binary LMC X-3 between February and June 2000. The observations covered both the soft and the hard X-ray spectral states. The hard-state spectra were dominated by a power-law component with a photon index Gamma ~1.9. The soft-state spectra consisted of a thermal component with a multi-colour disk temperature T_in of ~ 0.9 keV and a power-law tail with Gamma ~ 2.7. The model in which the X-rays from LMC X-3 in the high-soft state are powered by a strong stellar wind from a massive companion is not supported by the small line-of-sight absorption (n_H <~ 10²¹ cm^-2) deduced from the RGS data. The transition from the soft to the hard state appears to be a continuous process associated with the changes in the mass-transfer rate.