A unique X-ray unabsorbed Seyfert 2 galaxy IRAS F01475-0740

Abstract

X-ray unabsorbed Seyfert 2 galaxies appear to have X-ray absorption column densities that are too low (NH < 10^22 cm-2) to explain the absence of broad emission lines in their optical spectra, challenging the standard AGN unification model. In this paper we report Suzaku exposure on the X-ray unabsorbed Seyfert 2 galaxy IRAS F01475-0740, in which a hidden broad line region was detected through spectropolarimetric observation. The X-ray data show rapid and significant variations on time scales down to 5 ks, indicating that we are viewing its central engine directly. A newly obtained optical spectrum and previous optical/X-ray data suggest that state transition is unlikely in this source. These make IRAS F01475-0740 a very peculiar X-ray unabsorbed Seyfert 2 galaxy which can only be explained by absorption from materials with abnormally high dust-to-gas ratio (by a factor of > 4 larger than Galactic). This is in contrast to most AGNs, which typically show dust-to-gas ratios 3 - 100 times lower than the Galactic.

arXiv comment13 pages, 3 figures, 1 table, accepted to the Astrophysical Journal Letters

References in corpus (24)

• The distribution of absorbing column densities among Seyfert 2 galaxies
• A 3 dimensional diagnostic diagram for Seyfert 2s: probing X-ray absorption and Compton thickness
• The X-ray to optical-UV luminosity ratio of X-ray selected Type 1 AGN in XMM-COSMOS
• Dust in active nuclei. I. Evidence for "anomalous" properties
• X-ray obscuration and obscured AGN in the local universe
• Hidden Broad Line Seyfert 2 Galaxies in the CfA and 12micron Samples
• The distribution of silicate strength in Spitzer spectra of AGNs and ULIRGs
• Unabsorbed Seyfert 2 galaxies
• "Comets" orbiting a black hole
• Log N - Log S Relations and Spectral Properties of Sources from the ASCA Large Sky Survey --- their Implications for the Origin of the Cosmic X-ray Background (CXB)
• The Lack of BLR in Low Accretion Rate AGN as Evidence of their Origin in the Accretion Disk
• The Unified Model of Active Galactic Nuclei: II. Evolutionary Connection
• Investigating on the nuclear obscuration in two types of Seyfert 2 galaxies
• Indecent Exposure in Seyfert 2 Galaxies: A Close Look
• On the nature of unabsorbed Seyfert 2 galaxies
• X-QUEST: A Comprehensive X-ray Study of Local ULIRGs and QSOs
• Naked active galactic nuclei
• Infrared spectroscopy around 4micron of Seyfert 2 galaxies: Obscured broad line regions and coronal lines
• Ultra-luminous X-ray Sources in nearby galaxies from ROSAT HRI observations II. statistical properties
• Soft X-ray properties of a spectroscopically selected sample of interacting and isolated Seyfert galaxies
• The Soft-X-Ray Spectral Shape of X-Ray-Weak Seyferts
• X-ray Absorption and Optical Extinction in the Partially Obscured Seyfert Nucleus in Mrk 1393
• XMM Observations of the Seyfert 2 Galaxy NGC 7590: the Nature of X-ray Absorption
• A New Model for the Width of the Broad Emission Lines in AGN: The Role of the Accretion Rate

Cited by in corpus (9)

• Are X-ray Emitting Coronae around Super Massive Black Holes Outflowing?
• The Keck/OSIRIS Nearby AGN Survey (KONA) I. The Nuclear K-band Properties of Nearby AGN
• Application of Clumpy Torus Model to Broadband X-ray Spectra of Two Seyfert 1 Galaxies: IC 4329A and NGC 7469
• BAT AGN Spectroscopic Survey-XXIII. A New Mid-Infrared Diagnostic for Absorption in Active Galactic Nuclei
• A new sample of X-ray selected narrow emission-line galaxies. II. Looking for True Seyfert 2
• On the origin of X-ray oxygen emission-lines in obscured AGN
• The X-ray Nature of Nucleus in Seyfert 2 Galaxy NGC 7590
• Suzaku Confirms NGC~3660 is an Unabsorbed Seyfert 2
• The properties of the obscuring material of an AGNs sample from mid-IR and X-ray simultaneous fitting