Observing circumnuclear photoionized gas in high resolution spectra of Seyfert 1 Galaxies

I will present XMM-Newton-RGS observations of the Seyfert 1 Galaxies Mrk 335 and NGC 4051 that unveiled an emission line-rich spectrum during a low flux state of the AGN continuum.Line ratio diagnostics from H-like and He-like ions indicate that the emission lines arise in X-ray photoionized plasma. The physical properties of the line emitting material were derived using the CLOUDY photoionization code. Although the properties of the plasma cannot be uniquely determined, we found that the density of the X-ray photoionized gas in Mrk 335 is constrained at 99% c.l. to 10^9-10^{11} cm^{-3}, placing the gas within the inner edge of the optical Broad Line Region. For NGC 4051, the density and the location of the plasma are instead consistent with outer region of the AGN. I will briefly present other Seyfert 1 sources where X-ray photoionized emission lines possibly arise in the Broad Line Region and I will review the implication of these findings in a broader context.