An X-ray view of 82 LINERs with Chandra and XMM-Newton data

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Free access article

Issue		A&A Volume 506, Number 3, November II 2009


Page(s)		1107 - 1121
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361/200912288
Published online		22 July 2009

A&A 506, 1107-1121 (2009)
DOI: 10.1051/0004-6361/200912288

An X-ray view of 82 LINERs with Chandra and XMM-Newton data

O. González-Martín¹, J. Masegosa², I. Márquez², M. Guainazzi³, and E. Jiménez-Bailón⁴

¹ X-ray Astronomy Group, Department of Physics and Astronomy, Leicester University, Leicester LE1 7RH, UK
e-mail: gmo4@star.le.ac.uk; omaira@iaa.es (IAA)
² Instituto de Astrofísica de Andalucía, CSIC, Granada, Spain
³ European Space Astronomy Centre of ESA, P.O. Box 78, Villanueva de la Canada, 28691 Madrid, Spain
⁴ Instituto de Astronomía, Universidad Nacional Autónoma de Mexico, Apartado Postal 70-264, 04510 Mexico DF, Mexico

Received 3 April 2009 / Accepted 13 May 2009

Abstract
We present the results of a homogeneous X-ray analysis for 82 nearby low-ionisation, narrow emission-line regions (LINERs) selected from the catalogue of Carrillo et al. (1999, Rev. Mex. Astron. Astrofis., 35, 187). All sources have available Chandra (68 sources) and/or XMM-Newton (55 sources) observations. This is the largest sample of LINERs with X-ray spectral data (60 out of the 82 objects), and it significantly improves our previous analysis based on Chandra data for 51 LINERs (Gonzalez-Martin et al. 2006b, A&A, 460, 45). It both increases the sample size and adds XMM-Newton data. New models permit the inclusion of double absorbers in the spectral fits. Nuclear X-ray morphology is inferred from the compactness of detected nuclear sources in the hard band (4.5–8.0 keV). Sixty per cent of the sample shows a compact nuclear source and are classified as active galactic nucleus (AGN) candidates. The spectral analysis indicates that best fits involve a composite model: 1) absorbed primary continuum and 2) soft spectrum below 2 keV described by an absorbed scatterer and/or a thermal component. The resulting median spectral parameters and their standard deviations are $\langle\Gamma\rangle$ = 2.11 $\pm$ 0.52, $\langle kT\rangle$ = 0.54 $\pm$ 0.30 keV, ${\langle \log({\rm NH1}) \rangle }$ = 21.32 $\pm$ 0.71 and ${\langle \log({\rm NH2})\rangle }$ = 21.93 $\pm$ 1.36. We complement our X-ray results with an analysis of HST optical images and literature data on emission lines, radio compactness, and stellar population. After adding all these multiwavelength data, we conclude that evidence supports the AGN nature of their nuclear engine for 80% of the sample (66 out of 82 objects).

Key words: galaxies: active -- galaxies: nuclei -- galaxies: Seyfert -- X-rays: galaxies -- catalogs

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