AGNs with discordant optical and X-ray classification are not a physical family: diverse origin in two AGNs
Date Issued
2017
Author(s)
Ordovás-Pascual, I.
•
Mateos, S.
•
Carrera, F. J.
•
Wiersema, K.
•
Barcons, X.
•
•
•
Del Moro, A.
•
•
Abstract
Approximately 3-17 per cent of active galactic nuclei (AGNs) without detected rest-frame UV/optical broad emission lines (type-2 AGN) do not show absorption in X-rays. The physical origin behind the apparently discordant optical/X-ray properties is not fully understood. Our study aims at providing insight into this issue by conducting a detailed analysis of the nuclear dust extinction and X-ray absorption properties of two AGNs with low X-ray absorption and with high optical extinction, for which a rich set of high-quality spectroscopic data is available from XMM-Newton archive data in X-rays and XSHOOTER proprietary data at UV-to-NIR wavelengths. In order to unveil the apparent mismatch, we have determined the AV/NH and both the supermassive black hole and the host galaxy masses. We find that the mismatch is caused in one case by an abnormally high dust-to-gas ratio that makes the UV/optical emission to appear more obscured than in the X-rays. For the other object, we find that the dust-to-gas ratio is similar to the Galactic one but the AGN is hosted by a very massive galaxy so that the broad emission lines and the nuclear continuum are swamped by the star light and difficult to detect.
Volume
469
Issue
1
Start page
693
Issn Identifier
0035-8711
Ads BibCode
2017MNRAS.469..693O
Rights
open.access
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