Shimizu, TT;
Davies, RI;
Koss, M;
Ricci, C;
Lamperti, I;
Oh, K;
Schawinski, K;
... Tacconi, L; + view all
(2018)
BAT AGN Spectroscopic Survey. VIII. Type 1 AGN with Massive Absorbing Columns.
The Astrophysical Journal
, 856
(2)
, Article 154. 10.3847/1538-4357/aab09e.
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Abstract
We explore the relationship between X-ray absorption and optical obscuration within the BAT AGN Spectroscopic Survey (BASS), which has been collecting and analyzing the optical and X-ray spectra for 641 hard X-ray selected (E > 14 keV) active galactic nuclei (AGNs). We use the deviation from a linear broad Hα-to-X-ray relationship as an estimate of the maximum optical obscuration toward the broad line region (BLR) and compare the A V to the hydrogen column densities (${N}_{{\rm{H}}}$) found through systematic modeling of their X-ray spectra. We find that the inferred columns implied by A V toward the BLR are often orders of magnitude less than the columns measured toward the X-ray emitting region, indicating a small-scale origin for the X-ray absorbing gas. After removing 30% of Sy 1.9s that potentially have been misclassified due to outflows, we find that 86% (164/190) of the Type 1 population (Sy 1–1.9) are X-ray unabsorbed as expected based on a single obscuring structure. However, 14% (26/190), of which 70% (18/26) are classified as Sy 1.9, are X-ray absorbed, suggesting that the BLR itself is providing extra obscuration toward the X-ray corona. The fraction of X-ray absorbed Type 1 AGNs remains relatively constant with AGN luminosity and Eddington ratio, indicating a stable BLR covering fraction.
| Type: | Article |
|---|---|
| Title: | BAT AGN Spectroscopic Survey. VIII. Type 1 AGN with Massive Absorbing Columns |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/aab09e |
| Publisher version: | https://doi.org/10.3847/1538-4357/aab09e |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | galaxies: active; galaxies: nuclei; galaxies: Seyfert |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10091820 |
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