XMM-NEWTON VIEW OF THE MULTIPHASE WARM ABSORBER IN SEYFERT 1 GALAXY NGC 985

We present an analysis of a new XMM-Newton observation of the Seyfert 1 galaxy NGC 985. The European Photon Imaging Camera (EPIC) spectra present strong residuals to a single power-law model, indicating the presence of ionized absorbing gas and a soft excess. A broadband fit to the EPIC and RGS spectra shows that the continuum can be well fitted with a power law (Gamma approximate to 1.57) and a blackbody component (kT approximate to 0.09 keV). The RGS can be modeled either with two or three absorption components. In the two absorber model the low-ionization one, with log U approximate to .05 and log N-H approximate to 21.08, accounts for the presence of the Fe M-shell unresolved transition array (Fe VII-XIII), and the high-ionization component (log U approximate to 1.31 and log N-H approximate to 21.99) is required by the presence of several Fe L-shell transitions. The data suggest the presence of a third ionized component with higher ionization, so that the Fe L-shell absorption features are produced by two different components (one producing absorption by Fe XVII-XX, and the other absorption by Fe XX-XXII). However, the presence of the third absorbing component cannot be detected by means of an isolated absorption line in a significant way, so we consider this detection only as tentative. Interestingly, all ionization components have similar kinematics (with outflow velocities similar to 280 km s(-1)). In addition, whether two or three absorbers are considered, the components appear to be in pressure balance within 1 sigma. These results give further support to the idea that warm absorbers in active galactic nuclei consist of a two- or three-phase medium. We note that, while in the model with only two absorbers one of them (the high-ionization component) lies on an unstable branch of the thermal equilibrium curve, in the model with three absorbers all of the components lie on stable branches of the curve. This gives further plausibility to a multiphase absorber.