On the origin of soft X-rays in obscured AGN: answers from high-resolution spectroscopy with XMM–Newton
By M. Guainazzi, S. Bianchi. 2006
143 citations recorded by the source corpus.
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 O vii Heα triplet (once normalized to the O viii Lyα) coupled with the integrated luminosity in He- and H-like oxygen lines.
Subfields: Astronomy and Astrophysics
View Paper: https://www.semanticscholar.org/paper/26e048b761d31005b23d5cee04d94ebb13680c9f
How researchers see this paper
The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.
In Astronomy and Astrophysics
Citations in the corpus
- The active nuclei of z < 1.0 3CRR radio sources (2009, background): “…on scales comparable to that of the NLR, as is known in some Seyferts even in the presence of radio jets (e.g. Evans et al. 2006b); grating spectroscopy shows that the soft X-rays can be completely dominated by emission lines from material photoionized by the AGN (e.g. Guainazzi & Bianchi 2007).”
- An XMM–Newton spectral survey of 12 μm selected galaxies – I. X-ray data (2010, methodology): “The soft X-ray spectra of obscured AGN have been shown to consist partly of emission lines photo-ionised by the AGN (Guainazzi & Bianchi 2007).”
- BAT AGN Spectroscopic Survey. V. X-Ray Properties of the Swift/BAT 70-month AGN Catalog (2017, background): “…related to star formation (e.g., Iwasawa et al. 2011); ii) radiative-recombination continuum created by gas photoionized by the AGN (e.g., Bianchi et al. 2006; Guainazzi & Bianchi 2007); iii) scattering of the primary X-ray emission in Compton-thin circumnuclear material (e.g., Ueda et al. 2007).”
- X-ray spectral modelling of the AGN obscuring region in the CDFS: Bayesian model selection and catalogue (2014, background): “Explanations for this component include Thomson scattering off ionised material within the torus opening angle, which reflects the intrinsic spectrum into the line of sight (Krolik & Kallman 1987; Turner et al. 1997; Guainazzi & Bianchi 2007).”