A Uniformly Selected, All-sky, Optical AGN Catalog

Abstract

We have constructed an all-sky catalog of optical active galactic nuclei (AGNs) with z  < 0.09, based on optical spectroscopy, from the parent sample of galaxies in the 2MASS Redshift Survey, a near-complete census of the nearby universe. Our catalog consists of 1929 broad-line AGNs and 6562 narrow-line AGNs that satisfy the Kauffmann et al. criteria, of which 3607 also satisfy the Kewley et al. criteria. We also report emission-line widths, fluxes, flux errors, and signal-to-noise ratios (S/Ns) of all the galaxies in our spectroscopic sample, allowing users to customize the selection criteria. Although we uniformly processed the spectra of galaxies from a homogeneous parent sample, inhomogeneities persist owing to the differences in the quality of the obtained spectra, taken with different instruments, and the unavailability of spectra for ∼20% of the galaxies. We quantify how the differences in spectral quality affect not only the AGN detection rates but also ratios of broad-line to narrow-line AGNs. We find that the inhomogeneities primarily stem from the continuum S/N in the spectra near the emission lines of interest. We fit for the AGN fraction as a function of continuum S/N and assign AGN likelihoods to galaxies that were not identified as AGNs using the available spectra. This correction results in a catalog suitable for statistical studies. This work also paves the way for a truly homogeneous and complete nearby AGN catalog by identifying galaxies whose AGN status needs to be verified with higher-quality spectra, quantifying the spectral quality necessary to do so.