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arXiv · 0912.3719

The column density towards LMC X-1

Manfred Hanke·Joern Wilms·Michael A. Nowak·Laura Barragan·Norbert S. Schulz
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Abstract

We measure the neutral absorption towards the black hole X-ray binary system LMC X-1 from six archival soft X-ray spectra obtained with the gratings and/or CCD detectors on Chandra, XMM-Newton, and Swift. Four spectral models for the soft continuum have been investigated. While the powerlaw model may overestimate NH considerably, the others give consistent results. Taking the lower metalicity of the Large Magellanic Cloud into account, we find equivalent hydrogen column densities of N_H = (1.0-1.3)*10^22 cm^-2, with a systematic dependence on the orbital phase. This variation of the neutral absorption can nearly explain the orbital modulation of the soft X-ray flux recently detected with the All Sky Monitor (ASM) on the Rossi X-ray Timing Explorer (RXTE).

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Manfred Hanke, Joern Wilms, Michael A. Nowak, Laura Barragan, Norbert S. Schulz. 2009-12-18. The column density towards LMC X-1. https://doi.org/10.1051/0004-6361/200913583

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