BASS. XXVIII. Near-infrared Data Release 2: High-ionization and Broad Lines in Active Galactic Nuclei*
Jakob S. den Brok, Michael Koss, Benny Trakhtenbrot, Daniel Stern, Sebastiano Cantalupo, Isabella Lamperti, F. Ricci, Cláudio Ricci, Kyuseok Oh, F. E. Bauer, Rogério Riffel, A. Rodríguez-Ardila, Rudolf E. Bär, Fiona Harrison, Kohei Ichikawa, Julián E. Mejía-Restrepo, R. F. Mushotzky, Meredith C. Powell, Rozenn Boissay-Malaquin, Marko Stalevski, Ezequiel Treister, C. M. Urry, Sylvain Veilleux
Abstract
Abstract We present the BAT AGN Spectroscopic Survey (BASS) Near-infrared Data Release 2 (DR2), a study of 168 nearby ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover accent="true"> <mml:mrow> <mml:mi>z</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>¯</mml:mo> </mml:mrow> </mml:mover> <mml:mo>=</mml:mo> <mml:mn>0.04</mml:mn> </mml:math> , z < 0.6) active galactic nuclei (AGN) from the all-sky Swift Burst Array Telescope X-ray survey observed with the Very Large Telescope (VLT)/X-shooter in the near-infrared (NIR; 0.8–2.4 μ m). We find that 49/109 (45%) Seyfert 2 and 35/58 (60%) Seyfert 1 galaxies observed with VLT/X-shooter show at least one NIR high-ionization coronal line (CL; ionization potential χ > 100 eV). Comparing the emission of the [Si vi ] λ 1.9640 CL with the X-ray emission for the DR2 AGN, we find a significantly tighter correlation, with a lower scatter (0.37 dex) than that for the optical [O iii ] λ 5007 line (0.71 dex). We do not find any correlation between CL emission and the X-ray photon index Γ. We find a clear trend of line blueshifts with increasing ionization potential in several CLs, such as [Si vi ] λ 1.9640, [Si x ] λ 1.4300, [S viii ] λ 0.9915, and [S ix ] λ 1.2520, indicating the radial structure of the CL region. Finally, we find a strong underestimation bias in black hole mass measurements of Sy 1.9 using broad H α due to the presence of significant dust obscuration. In contrast, the broad Pa α and Pa β emission lines are in agreement with the M – σ relation. Based on the combined DR1 and DR2 X-shooter sample, the NIR BASS sample now comprises 266 AGN with rest-frame NIR spectroscopic observations, the largest set assembled to date.