Suzaku View of the Swift/BAT Active Galactic Nuclei (I): Spectral Analysis of Six AGNs and Evidence for Two Types of Obscured Population

Abstract

We present a systematic spectral analysis with Suzaku of six AGNs detected in the Swift/BAT hard X-ray (15--200 keV) survey, Swift J0138.6-4001, J0255.2-0011, J0350.1-5019, J0505.7-2348, J0601.9-8636, and J1628.1-5145. This is considered to be a representative sample of new AGNs without X-ray spectral information before the BAT survey. We find that the 0.5--200 keV spectra of these sources can be uniformly fit with a base model consisting of heavily absorbed (log $N_{\mathrm{H}}>23.5{\mathrm{cm}}^{-2}$) transmitted components, scattered lights, a reflection component, and an iron-K emission line. There are two distinct groups, three "new type" AGNs (including the two sources reported by \citealt{Ueda2007}) with an extremely small scattered fraction ($f_{\mathrm{scat}}<0.5$) and strong reflection component ($R=\Omega /2\pi \gtrsim 0.8$ where $\Omega$ is the solid angle of the reflector), and three "classical type" ones with $f_{\mathrm{scat}}>0.5$ and $R\lesssim 0.8$. The spectral parameters suggest that the new type has an optically thick torus for Thomson scattering ($N_{\mathrm{H}}\sim 10^{25}{\mathrm{cm}}^{-2}$) with a small opening angle $\theta \sim 20^{\circ }$ viewed in a rather face-on geometry, while the classical type has a thin torus ($N_{\mathrm{H}}\sim 10^{23-24}{\mathrm{cm}}^{-2}$) with $\theta \gtrsim 30^{\circ }$. We infer that a significant number of new type AGNs with an edge-on view is missing in the current all-sky hard X-ray surveys.

11 pages, 6 figures, accepted for publication in The Astrophysical Journal

References in corpus (18)

• The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
• A Unified, Merger-Driven Model for the Origin of Starbursts, Quasars, the Cosmic X-Ray Background, Supermassive Black Holes and Galaxy Spheroids
• Cosmological Evolution of the Hard X-ray AGN Luminosity Function and the Origin of the Hard X-ray Background
• The synthesis of the cosmic X-ray background in the Chandra and XMM-Newton era
• Hard X-ray Detector (HXD) on Board Suzaku
• Absorption Properties and Evolution of Active Galactic Nuclei
• Swift BAT Survey of AGN
• X-ray obscuration and obscured AGN in the local universe
• X-ray Spectral Survey with XMM--Newton of a Complete Sample of Nearby Seyfert Galaxies
• INTEGRAL/IBIS all-sky survey in hard X-rays
• Obscuring Material around Seyfert Nuclei with Starbursts
• Suzaku Observations of Active Galactic Nuclei Detected in the Swift/BAT Survey: Discovery of "New Type" of Buried Supermassive Black Holes
• Elusive Active Galactic Nuclei
• X-ray properties of an Unbiased Hard X-ray Detected Sample of AGN
• Extreme X-ray Iron Lines in Active Galactic Nuclei
• INTEGRAL/IBIS Extragalactic survey: 20-100 keV selected AGN
• Performance of the Charge Injection Capability of Suzaku XIS
• The complex X-ray spectrum of NGC 4507

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