The column density towards LMC X-1

Free access article

Issue		A&A Volume 509, January 2010


Article Number		L8
Number of page(s)		4
Section		Letters
DOI		http://dx.doi.org/10.1051/0004-6361/200913583
Published online		19 January 2010

A&A 509, L8 (2010)

Letter to the Editor

The column density towards LMC X-1

M. Hanke¹, J. Wilms¹, M. A. Nowak², L. Barragán¹ and N. S. Schulz²

¹ Dr. Karl Remeis-Observatory & ECAP, University of Erlangen-Nuremberg, Sternwartstr. 7, 96049 Bamberg, Germany e-mail: Manfred.Hanke@sternwarte.uni-erlangen.de
² MIT Kavli Institute for Astrophysics and Space Research, NE80-6077, 77 Mass. Ave., Cambridge, MA 02139, USA

Received: 2 November 2009
Accepted: 17 December 2009

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 are investigated. While the powerlaw model may overestimate considerably, the others give consistent results. Taking the lower metalicity of the Large Magellanic Cloud into account, we find equivalent hydrogen column densities of = (1.0-1.3) 10²² cm^-2, with a systematic dependence on the orbital phase. This variation in 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).

Key words: X-rays: individuals: LMC X-1 / X-rays: binaries / X-rays: ISM / galaxies: abundances

© ESO, 2010

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.