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

¹ Mullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, RH5 6NT, UK
² Research Centre for Theoretical Astrophysics, School of Physics, University of Sydney, NSW 2006, Australia
³ Columbia Astrophysics Laboratory, Columbia University, 550 West 120th Street, New York, NY 10027, USA
⁴ Space Research Organization of The Netherlands, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands

K. Wu

Received: 2 October 2000
Accepted: 10 November 2000

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 Γ ≈ 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 Γ ≈ 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.