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XMM-Newton Observations of H1743-322

ATel #1829; M. Hanke, J. Wilms, F. Fuerst (ECAP and Dr. Remeis-Observatory, FAU Erlangen-Nuremberg), M. A. Nowak (MIT), K. Pottschmidt (CRESST, GSFC and UMBC), on behalf of a larger collaboration
on 5 Nov 2008; 18:03 UT
Credential Certification: Joern Wilms (j.wilms@sternwarte.uni-erlangen.de)

Subjects: X-ray, Binary, Black Hole, Neutron Star, Transient

The Black Hole Candidate H1743-32/IGR J17464-3213 was observed with XMM-Newton on 29 September 2008, at the start of its current outburst (see ATELs #1739 and #1745 for information on the start of the outburst, and ATELs #1766, #1779, #1780, #1804, #1808, #1813 for further information on the evolution of the source after the XMM-Newton observation). Here, we report on the analysis of the pipeline processed XMM-Newton data from the EPIC-pn camera, which was operated in its timing mode. The 1-10keV spectrum can be well described with a rather strongly absorbed (NH=1.78(1)e22 cm-2) power law with photon index Gamma=1.37(1) (all uncertainties are at the 90% level). A possible slight softening can be modeled with an accretion disk spectrum (diskbb, inner temperature 0.10(1)keV). The absorbed 1-10keV flux is 7.7e-10 erg/s/cm^2 (unabsorbed: 1e-9 erg/s/cm^2). Contrary to most other black hole transients in outburst, no clear relativistically broadened Fe Kalpha line is visible in the data. The 90% upper limit for the equivalent width of a line from a maximally rotating black hole is 150eV. The absence of a relativistic line, however, might have to be due to the rather low flux observation necessitated by the telemetry limits of the EPIC-pn timing mode (observations in the more sensitive modified timing mode could not be performed for scheduling reasons). The Swift-BAT and the RXTE-ASM monitoring of the source shows that the source has now declined and that the outburst is about to be over.