TY - JOUR
T1 - BASS. XXIV. the BASS DR2 Spectroscopic Line Measurements and AGN Demographics
AU - Oh, Kyuseok
AU - Koss, Michael J.
AU - Ueda, Yoshihiro
AU - Stern, Daniel
AU - Ricci, Claudio
AU - Trakhtenbrot, Benny
AU - Powell, Meredith C.
AU - Den Brok, Jakob S.
AU - Lamperti, Isabella
AU - Mushotzky, Richard
AU - Ricci, Federica
AU - Bär, Rudolf E.
AU - Rojas, Alejandra F.
AU - Ichikawa, Kohei
AU - Riffel, Rogério
AU - Treister, Ezequiel
AU - Harrison, Fiona
AU - Urry, C. Megan
AU - Bauer, Franz E.
AU - Schawinski, Kevin
N1 - Publisher Copyright:
© 2022. The Author(s). Published by the American Astronomical Society.
PY - 2022/7/1
Y1 - 2022/7/1
N2 - We present the second catalog and data release of optical spectral line measurements and active galactic nucleus (AGN) demographics of the BAT AGN Spectroscopic Survey, which focuses on the Swift-BAT hard X-ray detected AGNs. We use spectra from dedicated campaigns and publicly available archives to investigate spectral properties of most of the AGNs listed in the 70 month Swift-BAT all-sky catalog; specifically, 743 of the 746 unbeamed and unlensed AGNs (99.6%). We find a good correspondence between the optical emission line widths and the hydrogen column density distributions using the X-ray spectra, with a clear dichotomy of AGN types for N H = 1022 cm-2. Based on optical emission-line diagnostics, we show that 48%-75% of BAT AGNs are classified as Seyfert, depending on the choice of emission lines used in the diagnostics. The fraction of objects with upper limits on line emission varies from 6% to 20%. Roughly 4% of the BAT AGNs have lines too weak to be placed on the most commonly used diagnostic diagram, [O iii]λ5007/Hβ versus [N ii]λ6584/Hα, despite the high signal-to-noise ratio of their spectra. This value increases to 35% in the [O iii]λ5007/[O ii]λ3727 diagram, owing to difficulties in line detection. Compared to optically selected narrow-line AGNs in the Sloan Digital Sky Survey, the BAT narrow-line AGNs have a higher rate of reddening/extinction, with Hα/Hβ > 5 (∼36%), indicating that hard X-ray selection more effectively detects obscured AGNs from the underlying AGN population. Finally, we present a subpopulation of AGNs that feature complex broad lines (34%, 250/743) or double-peaked narrow emission lines (2%, 17/743).
AB - We present the second catalog and data release of optical spectral line measurements and active galactic nucleus (AGN) demographics of the BAT AGN Spectroscopic Survey, which focuses on the Swift-BAT hard X-ray detected AGNs. We use spectra from dedicated campaigns and publicly available archives to investigate spectral properties of most of the AGNs listed in the 70 month Swift-BAT all-sky catalog; specifically, 743 of the 746 unbeamed and unlensed AGNs (99.6%). We find a good correspondence between the optical emission line widths and the hydrogen column density distributions using the X-ray spectra, with a clear dichotomy of AGN types for N H = 1022 cm-2. Based on optical emission-line diagnostics, we show that 48%-75% of BAT AGNs are classified as Seyfert, depending on the choice of emission lines used in the diagnostics. The fraction of objects with upper limits on line emission varies from 6% to 20%. Roughly 4% of the BAT AGNs have lines too weak to be placed on the most commonly used diagnostic diagram, [O iii]λ5007/Hβ versus [N ii]λ6584/Hα, despite the high signal-to-noise ratio of their spectra. This value increases to 35% in the [O iii]λ5007/[O ii]λ3727 diagram, owing to difficulties in line detection. Compared to optically selected narrow-line AGNs in the Sloan Digital Sky Survey, the BAT narrow-line AGNs have a higher rate of reddening/extinction, with Hα/Hβ > 5 (∼36%), indicating that hard X-ray selection more effectively detects obscured AGNs from the underlying AGN population. Finally, we present a subpopulation of AGNs that feature complex broad lines (34%, 250/743) or double-peaked narrow emission lines (2%, 17/743).
UR - http://www.scopus.com/inward/record.url?scp=85135281449&partnerID=8YFLogxK
U2 - 10.3847/1538-4365/ac5b68
DO - 10.3847/1538-4365/ac5b68
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AN - SCOPUS:85135281449
SN - 0067-0049
VL - 261
JO - Astrophysical Journal, Supplement Series
JF - Astrophysical Journal, Supplement Series
IS - 1
M1 - 4
ER -