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.
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Guy et al., The Spectroscopic Data Processing Pipeline for the Dark Energy Spectroscopic Instrument, Astron
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We describe the spectroscopic data processing pipeline of the Dark Energy Spectroscopic Instrument (DESI), which is conducting a redshift survey of about 40 million galaxies and quasars using a purpose-built instrument on the 4-m Mayall Telescope at Kitt Peak National Observatory. The main goal of DESI is to measure with unprecedented precision the expansion history of the Universe with the Baryon Acoustic Oscillation technique and the growth rate of structure with Redshift Space Distortions. Ten spectrographs with three cameras each disperse the light from 5000 fibers onto 30 CCDs, covering the near UV to near infrared (3600 to 9800 Angstrom) with a spectral resolution ranging from 2000 to 5000. The DESI data pipeline generates wavelength- and flux-calibrated spectra of all the targets, along with spectroscopic classifications and redshift measurements. Fully processed data from each night are typically available to the DESI collaboration the following morning. We give details about the pipeline's algorithms, and provide performance results on the stability of the optics, the quality of the sky background subtraction, and the precision and accuracy of the instrumental calibration. This pipeline has been used to process the DESI Survey Validation data set, and has exceeded the project's requirements for redshift performance, with high efficiency and a purity greater than 99 percent for all target classes.
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DESI DR2 and ACT DR6 data yield 17σ LRG-velocity, 8.3σ ELG-velocity, and 6.8σ QSO-velocity detections plus a 3.1σ velocity-velocity signal, producing f_NL^loc = 15.9_{-34.4}^{+34.6} from the velocity field.
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.
DESI DR2 BAO data exhibits 2.3 sigma tension with CMB in Lambda-CDM but prefers evolving dark energy (w0 > -1, wa < 0) at 3.1 sigma with CMB and 2.8-4.2 sigma when including supernovae.
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.
DESI measures BAO scales in six redshift bins with 0.52% combined precision using 5.7 million objects, detecting the signal at up to 9.1 sigma and finding larger scales than Planck LCDM at z<0.8.
Combining FAST and DESI data for 2.5 million galaxies shows cosmic atomic hydrogen density declined by only a factor of 1.35 over 4.5 Gyr, far less than the 2.46-fold decline in star formation.
DESI LAE clustering measurements give a linear bias of 2.31-2.62 with constraints on radiative transfer effects and halo occupation from correlation functions and power spectra.
High-significance kSZ measurements around LRGs show gas is redistributed beyond gravitational collapse and imply more efficient feedback in group-scale halos than in standard hydrodynamical models.
A heuristic power-spectrum rescaling applied to DESI DR1 BAO data plus CMB acoustic scale anchor yields H0 values of 69.2 to 70.3 km/s/Mpc at sub-2% precision across three independent late-time datasets.
Using idealized synthetic data, knowing the true continuum in Lyα forest auto- and cross-correlations reduces uncertainties on the AP parameter and Ω_m by ~10%, with extension to 240 h^{-1}Mpc scales adding up to ~15% further improvement equivalent to a 40% larger survey area.
DESI DR1 full-shape clustering yields Ω_m = 0.2962 ± 0.0095 and σ_8 = 0.842 ± 0.034 in flat ΛCDM, tightening to H_0 = 68.40 ± 0.27 km/s/Mpc with CMB and DESY3, while favoring w_0 > -1, w_a < 0 and limiting neutrino mass sum to < 0.071 eV.
DESI DR1 full-shape galaxy clustering constrains Omega_m = 0.296 ± 0.010, H0 = 68.63 ± 0.79 km/s/Mpc, and sigma_8 = 0.841 ± 0.034, consistent with LambdaCDM and Planck.
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.
Probabilistic spectroscopic classification of 251k LoTSS radio sources yields the largest high-confidence sample and confirms LERGs accrete below ~1% Eddington while HERGs accrete above it.
FolpsD combines EFT power spectrum and tree-level bispectrum with damping to enable joint analyses that improve cosmological constraints from DESI-like galaxy mocks by up to 30% on As and omega_cdm while extending the usable k-range without significant biases for LRG samples.
Cross-correlating LRG and QSO samples in DESI DR1 yields f_NL^loc = 2.1 with 68% uncertainties of +8.8 and -8.3, an incremental improvement over auto-correlations alone.
Combining LRG and ELG tracers with bias weighting improves BAO constraints by 11% on alpha_iso and 7% on alpha_AP in DESI DR1 data for the 0.8<z<1.1 bin.
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.
DESI DR1 bispectrum plus DR2 BAO data raise σ8 and S8 by ~1.1-1.2σ while tightening uncertainties, shift DESI-only w0waCDM toward ΛCDM, produce a 2.8σ deviation from ΛCDM when combined with CMB, and yield a neutrino mass sum posterior of 0.26±0.17 eV.
Property-dependent systematic weights derived separately on ELG subsamples, with separate DES footprint treatment, mitigate spurious clustering in ~10% of subsamples but are not optimal for the full sample.
DESI DR1 constrains the modified gravity parameter to log10 |f_R0| < -4.59 at 95% CL, implying no detectable fifth force on scales below about 18 Mpc.
Extended analysis of DESI DR2 data confirms robust evidence for dynamical dark energy with phantom crossing preference, stable under parametric and non-parametric modeling.
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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Constraints on Neutrino Physics from DESI DR2 BAO and DR1 Full Shape
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.