Abstract

We present measurements of broad emission lines and virial estimates of supermassive black hole masses (M-BH) for a large sample of ultrahard X-ray-selected active galactic nuclei (AGNs) as part of the second data release of the BAT AGN Spectroscopic Survey (BASS/DR2). Our catalog includes M-BH estimates for a total of 689 AGNs, determined from the H alpha, H beta), Mg II lambda 2798, and/or C IV lambda 1549 broad emission lines. The core sample includes a total of 512 AGNs drawn from the 70 month Swift/BAT all-sky catalog. We also provide measurements for 177 additional AGNs that are drawn from deeper Swift/BAT survey data. We study the links between M-BH estimates and line-of-sight obscuration measured from X-ray spectral analysis. We find that broad Ha emission lines in obscured AGNs (log(N-H/cm(-2)) > 22.0) are on average a factor of 8.0(-2.4)(+4.1) weaker relative to ultrahard X-ray emission and about 35 + 1 7 2 % narrower than those in unobscured sources (i.e., log(N-H/cm(-2)) 21.5). This indicates that the innermost part of the broad-line region is preferentially absorbed. Consequently, current single-epoch MBH prescriptions result in severely underestimated (>1 dex) masses for Type 1.9 sources (AGNs with broad Ha but no broad H beta)and/or sources with log(N-H/cm(-2)) greater than or similar to 22.0. We provide simple multiplicative corrections for the observed luminosity and width of the broad Ha component (L[bH alpha] and FWHM[bH alpha]) in such sources to account for this effect and to (partially) remedy MBH estimates for Type 1.9 objects. As a key ingredient of BASS/DR2, our work provides the community with the data needed to further study powerful AGNs in the low-redshift universe.