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The DESI Survey Validation: Results from Visual Inspection of the Quasar Survey Spectra

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arxiv 2208.08517 v3 pith:22QHO75D submitted 2022-08-17 astro-ph.GA astro-ph.CO

classification astro-ph.GAastro-ph.CO
keywords pipelinesurveyquasarsspectradesiquasarspectroscopicstandard
verification ladder T0 review T1 audit T2 compute T3 formal
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A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) of the optical spectroscopic data to quantify key survey metrics. In this paper we present results from VI of the quasar survey using deep coadded SV spectra. We show that the majority (~70%) of the main-survey targets are spectroscopically confirmed as quasars, with ~16% galaxies, ~6% stars, and ~8% low-quality spectra lacking reliable features. A non-negligible fraction of the quasars are misidentified by the standard spectroscopic pipeline but we show that the majority can be recovered using post-pipeline "afterburner" quasar-identification approaches. We combine these "afterburners" with our standard pipeline to create a modified pipeline to improve the overall quasar yield. At the depth of the main DESI survey both pipelines achieve a good-redshift purity (reliable redshifts measured within 3000 km/s) of ~99%; however, the modified pipeline recovers ~94% of the visually inspected quasars, as compared to ~86% from the standard pipeline. We demonstrate that both pipelines achieve an median redshift precision and accuracy of ~100 km/s and ~70 km/s, respectively. We constructed composite spectra to investigate why some quasars are missed by the standard spectroscopic pipeline and find that they are more host-galaxy dominated (i.e., distant analogs of "Seyfert galaxies") and/or dust reddened than the standard-pipeline quasars. We also show example spectra to demonstrate the overall diversity of the DESI quasar sample and provide strong-lensing candidates where two targets contribute to a single spectrum.

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Cited by 14 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Clustering of high-redshift quasars with DESI DR2

    astro-ph.CO 2026-06 unverdicted novelty 7.0 of 10

    DESI DR2 quasar sample yields bias b_Q(z=2.48)=3.61 that evolves as b(z)=0.230[(1+z)^2-6.565]+2.394, consistent with constant ~10^12 M_sun halo mass and weak luminosity dependence at fixed redshift.

  2. Cosmological analysis of the DESI DR1 Lyman alpha 1D power spectrum

    astro-ph.CO 2026-01 unverdicted novelty 7.0 of 10

    DESI DR1 Lyman-alpha data yields Δ²★=0.379±0.032 and n★=-2.309±0.019 at k★=0.009 km⁻¹s and z=3, sharpening N_eff, α_s, and β_s constraints by factors of 1.18-1.90 when combined with other probes.

  3. DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations

    astro-ph.CO 2024-04 accept novelty 7.0 of 10

    First-year DESI BAO data are consistent with flat LambdaCDM and, when combined with CMB, show a 2.5-3.9 sigma preference for evolving dark energy (w0 > -1, wa < 0) that strengthens with certain supernova datasets.

  4. AGN radiative feedback as the main regulator of [O III] outflow activity and obscuration in X-ray AGN

    astro-ph.GA 2026-06 accept novelty 6.5 of 10

    AGN radiation pressure, not black-hole mass, simultaneously boosts large-scale [O III] outflows and clears circumnuclear gas as Eddington ratio rises.

  5. Lyman-$\alpha$ forest holography: 3D predictions from 1D measurements

    astro-ph.CO 2026-07 conditional novelty 6.0 of 10

    One-dimensional Lyman-α forest power spectrum measurements, propagated through the ForestFlow emulator, predict three-dimensional clustering that matches DESI BAO and ACCEL-2 simulation results.

  6. Alcock-Paczynski Blinding Scheme for the Ly-$\alpha$ Forest Analysis

    astro-ph.CO 2026-07 accept novelty 6.0 of 10

    A catalog-level Alcock-Paczynski wavelength-shift blinding scheme for the Lyman-alpha forest robustly hides the expansion history and correctly shifts the BAO peak on DESI DR1 data and mocks.

  7. Limits on global cosmic birefringence using radio sources

    astro-ph.CO 2026-07 conditional novelty 6.0 of 10

    X-band radio sources yield μ_β = (0.2 ± 1.0)° for global cosmic birefringence, with stacking to ~0.6° and a forecast that ~10^5 sources could reach ~0.1° to test Planck claims.

  8. Cosmological neutrino mass: a frequentist overview in light of DESI

    astro-ph.CO 2025-07 accept novelty 6.0 of 10

    A frequentist profile-likelihood analysis of DESI, Planck, ACT, and eBOSS Lyman-alpha data yields Σmν < 53 meV (95% C.L.) in flat ΛCDM and a CMB-independent bound of 285 meV.

  9. DESI 2024 IV: Baryon Acoustic Oscillations from the Lyman Alpha Forest

    astro-ph.CO 2024-04 accept novelty 6.0 of 10

    DESI measures BAO from the Lyα forest at z_eff=2.33, reporting H(z) = (239.2 ± 4.8) (147.09 Mpc/rd) km/s/Mpc and DM(z) = (5.84 ± 0.14) (rd/147.09 Mpc) Gpc.

  10. Validation of the DESI DR2 Ly$\alpha$ forest full-shape analysis

    astro-ph.CO 2026-07 conditional novelty 5.0 of 10

    The DESI DR2 Lyman-alpha full-shape analysis passes validation for BAO and Alcock-Paczynski parameters on 400 mocks and blinded data, while f-sigma-8 is rejected due to a roughly 10% mock bias.

  11. Validation of the DESI DR2 Ly$\alpha$ forest full-shape analysis

    astro-ph.CO 2026-07 conditional novelty 5.0 of 10

    The DESI DR2 Lyman-alpha forest full-shape analysis passes validation for BAO and Alcock-Paczynski parameters on hundreds of mocks and blinded data, while the fσ8 growth-rate measurement is found biased and excluded.

  12. Constraints on Neutrino Physics from DESI DR2 BAO and DR1 Full Shape

    astro-ph.CO 2025-03 conditional novelty 5.0 of 10

    DESI DR2 BAO and full-shape data plus CMB yield ∑m_ν < 0.0642 eV (95% CL) under ΛCDM, in 3σ tension with oscillation lower limits, relaxed to <0.163 eV in w0waCDM.

  13. AGN radiative feedback as the main regulator of [O III] outflow activity and obscuration in X-ray AGN

    astro-ph.GA 2026-06 unverdicted novelty 4.0 of 10

    Higher Eddington ratio AGN exhibit increased [O III] outflow incidence and reduced obscuration, supporting radiative feedback as the regulator.

  14. DESI DR2 Results I: Baryon Acoustic Oscillations from the Lyman Alpha Forest

    astro-ph.CO 2025-03 accept novelty 4.0 of 10

    DESI DR2 delivers 0.65% precision BAO measurements from the LyA forest at z_eff=2.33, with D_H/r_d = 8.632 ± 0.098 ± 0.026 and D_M/r_d = 38.99 ± 0.52 ± 0.12.

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