XMM-Newton observation of 4U 1543-475: the X-ray spectrum of a stellar-mass black-hole at low luminosity

Abstract

We report the results of an observation of the galactic black-hole binary 4U 1543-475 performed by XMM-Newton on 2002 August 18, about two months after the start of an outburst detected by Rossi-XTE. Despite the relatively low flux of the source, corresponding to a luminosity Lx ~ 4x10^34 erg/s (i.e. about 10^(-5) times the Eddington luminosity), we could obtain a good quality spectrum thanks to the high throughput of the XMM-Newton EPIC instrument. The spectrum is well fit by a power law with photon index 1.9-2 without any evidence for iron emission lines or for thermal emission from an accretion disk. We could estimate an upper-limit on the disk bolometric luminosity as a function of the colour temperature: it is always lower than ~10^33 erg/s, i.e. less than 10 % of the source total luminosity. Finally, we evaluated that the disk colour temperature must satisy the condition kTcol<0.25 keV in order to obtain an acceptable value for the disk inner radius.

4 pages, 3 figures, 2 tables. Accepted for publication by Astronomy & Astrophysics Letters

References in corpus (5)

• The European Photon Imaging Camera on XMM-Newton: The MOS Cameras
• New Evidence for Black Hole Event Horizons from Chandra
• Complete and Simultaneous Spectral Observations of the Black-Hole X-ray Nova XTE J1118+480
• Spectral and Timing Evolution of the Black Hole X-ray Nova 4U 1543-47 During its 2002 Outburst
• Spectral and Temporal Behavior of the Black Hole Candidate XTE J1118+480 as Observed with BeppoSAX

Cited by in corpus (5)

• The gas-to-extinction ratio and the gas distribution in the Galaxy
• On the origin of black hole X-ray emission in quiescence: Chandra observations of XTE J1550-564 and H 1743-322
• Understanding X-ray Irradiation in Low-Mass X-ray Binaries directly from their Light-Curves
• The hard to soft spectral transition in LMXBs - affected by recondensation of gas into an inner disk
• Fourier resolved spectroscopy of 4U 1543-47 during the 2002 outburst