Digest
Survey of 24 WISE W4–bright, optically faint/red SDSS Stripe 82 candidates confirms 23 luminous Type‑2 quasars at z = 0.88–3.49 using Gemini/GNIRS plus Keck/LRIS and KCWI spectra. About one‑third (8/23) unexpectedly show broad Hα (FWHM > 2000 km/s) while sharing SEDs with JWST “little red dots,” marking them as lower‑z analogues of heavily obscured broad‑line AGN. The sample also exhibits relatively weak [O III] λ5007 given their high bolometric luminosities, and the authors construct a new Type‑2 QSO composite spectrum. Results demonstrate that simple mid‑IR plus extreme r−W4 color selection efficiently recovers a spectroscopically diverse obscured quasar population at cosmic noon, informing SMBH growth demographics that connect to the LRD population.
Key figures to inspect
- Target selection plane: r − W4 versus W4 (or r magnitude), showing the Stripe 82 DOG cut (e.g., r > 23 or r − W4 > 8.4) and the >5 mJy W4 threshold; verify where the confirmed Type‑2s and broad‑Hα objects sit relative to these cuts.
- GNIRS rest‑optical spectra around Hα for the 8 broad‑line sources; inspect line decompositions, measured FWHM (>2000 km/s), and any accompanying narrow components or [N II]/[S II] constraints.
- LRIS/KCWI rest‑UV spectra displaying Lyα, C IV, and other lines across the sample; compare profile diversity and widths between pure narrow‑line objects and the broad‑Hα subset.
- [O III] λ5007 luminosity versus Lbol (or mid‑IR luminosity) comparison plot; look for the systematic [O III] deficit relative to low‑z Type‑2 trends and outliers that drive the deviation.
- Type‑2 QSO composite spectrum built from this sample; check contributing objects, normalization, and key line ratios that encode the weak‑[O III] behavior and broad‑line fraction.