Query : 2013A&A...555A..44F

2013A&A...555A..44F - Astronomy and Astrophysics, volume 555A, 44-44 (2013/7-1)

X-ray view of four high-luminosity Swift/BAT AGN: unveiling obscuration and reflection with Suzaku.


Abstract (from CDS):

A complete census of obscured active galactic nuclei (AGN) is necessary to reveal the history of the super massive black hole (SMBH) growth and galaxy evolution in the Universe given the complex feedback processes and the fact that much of this growth occurs in an obscured phase. In this context, hard X-ray surveys and dedicated follow-up observations represent a unique tool for selecting highly absorbed AGN and for characterizing the obscuring matter surrounding the SMBH. Here we focus on the absorption and reflection occurring in highly luminous, quasar-like AGN, to study the relation between the geometry of the absorbing matter and the AGN nature (e.g. X-ray, optical, and radio properties), and to help to determine the column density dependency on the AGN luminosity. The Swift/BAT nine-month survey observed 153 AGN, all with ultra-hard X-ray BAT fluxes in excess of 10–11erg/cm2/s and an average redshift of 0.03. Among them, four of the most luminous BAT AGN (44.73<LogLBAT<45.31) were selected as targets of Suzaku follow-up observations: J2246.0+3941 (3C452), J0407.4+0339 (3C105), J0318.7+6828, and J0918.5+0425. The column density, scattered/reflected emission, the properties of the Fe K line, and a possible variability are fully analyzed. For the latter, the spectral properties from Chandra, XMM-Newton and Swift/XRT public observations were compared with the present Suzaku analysis, adding an original spectral analysis when none was available from the literature. Of our sample, 3C452 is the only certain Compton-thick AGN candidate because of i) the high absorption (NH∼4x1023cm–2) and strong Compton reflection; ii) the lack of variability; iii) the ``buried'' nature, i.e. the low scattering fraction (<0.5%) and the extremely low relative [OIII] luminosity. In contrast 3C105 is not reflection-dominated, despite the comparable column density, X-ray luminosity and radio morphology, but shows a strong long-term variability in flux and scattering fraction, consistent with the soft emission being scattered from a distant region (e.g., the narrow emission line region). The sample presents high (>100) X-to-[OIII] luminosity ratios, with an extreme value of RX[OIII]∼800 for 3C452, confirming the [OIII] luminosity to be affected by residual extinction in presence of mild absorption, especially for ``buried'' AGN such as 3C452. Three of our targets are powerful FRII radio galaxies, which is shown by their high luminosity and absorption; this makes them the most luminous and absorbed AGN of the BAT Seyfert survey despite the inversely proportional NH-LX relation.

Abstract Copyright:

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

Simbad objects: 6

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Number of rows : 6
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2024
1 LEDA 3095635 Sy2 03 18 19.1052680424 +68 29 31.942230432           ~ 62 0
2 3C 105.0 Sy2 04 07 16.4671273272 +03 42 25.813809432   18.5       ~ 229 1
3 2MASX J09180027+0425066 Sy2 09 18 00.2606031984 +04 25 06.162946284   18.90 18.13     ~ 18 0
4 NGC 4945 Sy2 13 05 27.279 -49 28 04.44   9.31 14.40 7.55   ~ 1478 2
5 LEDA 68751 Sy1 22 23 49.5400938871 -02 06 12.859452336   16.93 15.77 16.02   ~ 485 2
6 3C 452 Sy2 22 45 48.7616172744 +39 41 15.906782184   17.60 16.56     ~ 377 1

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