Volume 418, Number 2, May I 2004
|Page(s)||459 - 463|
|Published online||09 April 2004|
XMM-Newton observations of the BL Lac MS 0205.7+3509: A dense, low-metallicity absorber
Niels Bohr Institute, Astronomical Observatory, University of Copenhagen, Juliane-Maries Vej 30, 2100 Copenhagen Ø, Denmark
2 X-Ray Astronomy Group, Department of Physics and Astronomy, Leicester University, Leicester LE1 7RH, UK
3 Dept. of Experimental Physics, University College Dublin, Dublin 4, Ireland
4 Laboratory for High Energy Astrophysics, Code 662, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
5 Universities Space Research Association
6 Dept. of Applied Physics and Instrumentation, Cork Institute of Technology, Cork, Ireland
7 Joint Center for Astrophysics, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
8 Johns Hopkins University, Baltimore, MD 21218, USA
9 Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309-0389, USA
10 National Optical Astronomy Observatory, 950 N. Cherry Ave., Tucson, AZ 85719, USA
11 University of Alaska, 3211 Providence Dr., BMB 212, Anchorage, AK 99508, USA
Corresponding author: D. Watson, firstname.lastname@example.org
Accepted: 26 January 2004
The high-frequency-peaked BL Lac, MS 0205.7+3509 was observed twice with XMM-Newton. Both X-ray spectra are synchrotron-dominated, with mean 0.2–10 keV fluxes of and erg cm-2 s-1. The X-ray spectra are well fit by a power-law with absorption above the Galactic value, however no absorption edges are detected, implying a low metallicity absorber () or an absorber with redshift above one (best-fit for an absorber with solar abundances). In either case the absorbing column density must be cm-2. A new optical spectrum is presented, with a absorption doublet detected at , but no other significant features. The optical spectrum shows little reddening, implying a low dust to gas ratio in the absorber. MS 0205.7+3509 must therefore be viewed through a high column density, low-metallicity gas cloud, probably at and associated with the galaxy that has been shown to be within ´´ of the BL Lac.
Key words: galaxies: BL Lacertae objects: individual: MS 0205.7+3509 / galaxies: active / X-rays: galaxies
© ESO, 2004
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