XMM-Newton observations of the BL Lac MS0205.7 3509: a dense, low-metallicity absorberReport as inadecuate



 XMM-Newton observations of the BL Lac MS0205.7 3509: a dense, low-metallicity absorber


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The high-frequency-peaked BL Lac, MS0205.7+3509 was observed twice with XMM-Newton. Both X-ray spectra are synchrotron-dominated, with mean 0.2-10keV fluxes of 2.80+-0.01 and 3.34+-0.02 E-12 erg-cm^2-s. 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 Z \sun = 0.04+0.03-0.01 or an absorber with redshift above one best-fit z=2.1 for an absorber with solar abundances. In either case the absorbing column density must be ~9E21 cm^-2. A new optical spectrum is presented, with a MgII absorption doublet detected at z=0.351, but no other significant features. The optical spectrum shows little reddening, implying a low dust to gas ratio in the absorber. MS0205.7+3509 must therefore be viewed through a high column density, low-metallicity gas cloud, probably at z=0.351 and associated with the galaxy that has been shown to be within ~2- of the BL Lac.



Author: D. Watson; B. McBreen; L. Hanlon; J. N. Reeves; N. Smith; E. Perlman; J. Stocke; T. A. Rector

Source: https://archive.org/







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