The Active Galactic Nuclei in the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX). I. Sample Selection

Abstract

We present the first active galactic nuclei (AGN) catalog of the Hobby–Eberly Telescope Dark Energy Experiment Survey (HETDEX) observed between 2017 January and 2020 June. HETDEX is an ongoing spectroscopic survey (3500–5500 Å) with no target preselection based on magnitudes, colors or morphologies, enabling us to select AGN based solely on their spectral features. Both luminous quasars and low-luminosity Seyferts are found in our catalog. AGN candidates are selected with at least two significant AGN emission lines, such as the Lyα and C iv λ1549 line pair, or with a single broad emission line with FWHM > 1000 km s−1. Each source is further confirmed by visual inspections. This catalog contains 5322 AGN, covering an effective sky coverage of 30.61 deg2. A total of 3733 of these AGN have secure redshifts, and we provide redshift estimates for the remaining 1589 single broad-line AGN with no crossmatched spectral redshifts from the Sloan Digital Sky Survey Data Release 14 of QSOs. The redshift range of the AGN catalog is 0.25 < z < 4.32, with a median of z = 2.1. The bolometric luminosity range is 109–1014 L ☉ with a median of 1012 L ☉. The median r-band magnitude of our AGN catalog is 21.6 mag, with 34% having r > 22.5, and 2.6% reaching the detection limit at r ∼ 26 mag of the deepest imaging surveys we searched. We also provide a composite spectrum of the AGN sample covering 700–4400 Å.