EDP Sciences
Free Access
Volume 448, Number 2, March III 2006
Page(s) 499 - 511
Section Extragalactic astronomy
DOI https://doi.org/10.1051/0004-6361:20054091
A&A 448, 499-511 (2006)
DOI: 10.1051/0004-6361:20054091

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
    e-mail: Stefano.Bianchi@sciops.esa.int
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

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