Probing the complex and variable X-ray absorption of Markarian 6 with XMM-Newton

We report on an X-ray observation of the Seyfert 1.5 galaxy Mrk 6 obtained with the EPIC instruments on board XMM-Newton. Archival BeppoSAX Phoswich Detection System data from 18-120 keV were also used to constrain the underlying hard power-law continuum. The results from our spectral analyses generally favor a double partial-covering model, although other spectral models, such as absorption by a mixture of partially ionized and neutral gas, cannot be firmly ruled out. Our best-fitting model consists of a power law with a photon index of Gamma = 1.81(-0.20)(+0.22) and partial covering with large column densities up to N-H similar to 10(23) cm(-2). We also detect a narrow emission line consistent with Fe Kalpha fluorescence at 6.45(-0.04)(+0.03) keV with an equivalent width of 93(-20)(+26) eV. Joint analyses of XMM-Newton, ASCA, and BeppoSAX data further provide evidence for both spectral variability (a factor of similar to2 change in absorbing column) and absorption-corrected flux variations (by similar to60%) during the similar to4 yr period probed by the observations.