The soft X-ray/NLR connection: a single photoionized medium?S. Bianchi1, M. Guainazzi1 and M. Chiaberge2, 3
1 XMM-Newton Science Operations Center, European Space Astronomy Center, ESA, Apartado 50727, 28080 Madrid, Spain
2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
3 INAF - Istituto di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
(Received 23 August 2005 / Accepted 29 October 2005 )
We present a sample of 8 nearby Seyfert 2 galaxies observed by HST and Chandra. All of the sources present soft X-ray emission which is coincident in extension and overall morphology with the [O III] emission. The spectral analysis reveals that the soft X-ray emission of all the objects is likely to be dominated by a photoionized gas. This is strongly supported by the 190 ks combined XMM-Newton/RGS spectrum of Mrk 3, which different diagnostic tools confirm as being produced in a gas in photoionization equilibrium with an important contribution from resonant scattering. We tested with the code CLOUDY a simple scenario where the same gas photoionized by the nuclear continuum produces both the soft X-ray and the [O III] emission. Solutions satisfying the observed ratio between the two components exist, and require the density to decrease with radius roughly like r-2, similarly to what often found for the Narrow Line Region.
Key words: galaxies: Seyfert -- X-rays: galaxies
© ESO 2006