2007/06/08 by Yoshihiro Ueda, Satoshi Eguchi, S. Eguchi +11 · 6 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geometry #Optics #Physics #Reflection (computer programming) #Scattering #Spectral line #Supermassive black hole #Swift #Torus #astro-ph
paper · pdf · doi:10.1086/520576
4 pages, 3 figures, accepted for publication in ApJ Letter
arxiv created 2007/06/08 · openalex publication_date 2007/07/18 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the Suzaku broadband observations of two AGNs detected by the Swift BAT hard X-ray (>15 keV) survey that did not have previous X-ray data, SWIFT J0601.9-8636 and SWIFT J0138.6-4001. The Suzaku spectra reveal in both objects a heavily absorbed power-law component with a column density of N H ≃ 10 23.5 -10 24 cm -2 that dominates above 10 keV and an intense reflection component with a solid angle ≳2π from a cold, optically thick medium. We find that these AGNs have an extremely small fraction of scattered light from the nucleus, ≲0.5% with respect to the intrinsic power-law component. This indicates that they are buried in a very geometrically thick torus with a small opening angle and/or have an unusually small amount of gas responsible for scattering. In the former case, the geometry of SWIFT J0601.9-8636 should be nearly face-on as inferred from the small absorption for the reflection component. The discovery of two such objects in this small sample implies that there must be a significant number of yet unrecognized, very Compton thick AGNs viewed at larger inclination angles in the local universe, which are difficult to detect even in the currently most sensitive optical or hard X-ray surveys.