SIMBAD references

2007MNRAS.374.1290G - Mon. Not. R. Astron. Soc., 374, 1290-1302 (2007/February-1)

On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM-Newton.


Abstract (from CDS):

We present results of a high-resolution soft X-ray (0.2-2 keV) spectroscopic study of a sample of 69 nearby obscured active galactic nuclei (AGNs) observed with the reflection grating spectrometer (RGS) onboard XMM-Newton. This is the largest sample ever studied with this technique so far. The main conclusions of our study can be summarized as follows: (i) narrow radiative recombination continua are detected in about 36 per cent of the objects in our sample (in 26 per cent their intrinsic width is ≤10 eV); (ii) higher order transitions are generally enhanced with respect to pure photoionization, indicating that resonant scattering plays an important role in the ionization/excitation balance. These results support the scenario, whereby the active nucleus is responsible for the X-ray `soft excess' almost ubiquitously observed in nearby obscured AGNs via photoionization of circumnuclear gas. They confirm on a statistical basis the conclusions drawn from the detailed study of the brightest spectra in the sample. Furthermore, we propose a criterion to statistically discriminate between AGN-photoionized sources and starburst galaxies, based on intensity of the forbidden component of the Ovii Heα triplet (once normalized to the Oviii Lyα) coupled with the integrated luminosity in He- and H-like oxygen lines.

Abstract Copyright: 2007 The Authors. Journal compilation © 2007 RAS

Journal keyword(s): galaxies: active - galaxies: nuclei - galaxies: Seyfert - X-rays: galaxies

Simbad objects: 107

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