The NuSTAR view of the true Type 2 Seyfert NGC3147

Abstract

We present the first NuSTAR observation of a 'true' Type 2 Seyfert galaxy. The 3-40 keV X-ray spectrum of NGC3147 is characterised by a simple power-law, with a standard Γ~1.7 and an iron emission line, with no need for any further component up to ~40 keV. These spectral properties, together with significant variability on time-scales as short as weeks (as shown in a 2014 Swift monitoring campaign), strongly support an unobscured line-of-sight for this source. An alternative scenario in terms of a Compton-thick source is strongly disfavoured, requiring an exceptional geometrical configuration, whereas a large fraction of the solid angle to the source is filled by a highly ionised gas, whose reprocessed emission would dominate the observed luminosity. Moreover, in this scenario the implied intrinsic X-ray luminosity of the source would be much larger than the value predicted by other luminosity proxies, like the [OIII]λ5007 emission line extinction-corrected luminosity. Therefore, we confirm with high confidence that NGC3147 is a true Type 2 Seyfert galaxy, intrinsically characterised by the absence of a BLR.

arXiv comment5 pages, 5 figures, accepted for publication in MNRAS

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• The Black Hole Masses and Eddington Ratios of Type 2 Quasars
• MUSE observations of a changing-look AGN I: The re-appearance of the broad emission lines
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• The Frequency of Intrinsic X-ray Weakness Among Broad Absorption Line Quasars
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