Target Selection and Validation of DESI Luminous Red Galaxies
read the original abstract
The Dark Energy Spectroscopic Instrument (DESI) is carrying out a 5-year survey that aims to measure the redshifts of tens of millions of galaxies and quasars, including 8 million luminous red galaxies (LRGs) in the redshift range of $0.4<z<{\sim}\,1.0$. Here we present the selection of the DESI LRG sample and assess its spectroscopic performance using data from Survey Validation (SV) and the first 2 months of the Main Survey. The DESI LRG sample, selected using $g$, $r$, $z$, and $W1$ photometry from the DESI Legacy Imaging Surveys, is highly robust against imaging systematics. The sample has a target density of 605 deg$^{-2}$ and a comoving number density of $5\times10^{-4}\ h^3\mathrm{Mpc}^{-3}$ in $0.4<z<0.8$; this is a significantly higher density than previous LRG surveys (such as SDSS, BOSS and eBOSS) while also extending to $z \sim 1$. After applying a bright star veto mask developed for the sample, $98.9\%$ of the observed LRG targets yield confident redshifts (with a catastrophic failure rate of $0.2\%$ in the confident redshifts), and only $0.5\%$ of the LRG targets are stellar contamination. The LRG redshift efficiency varies with source brightness and effective exposure time, and we present a simple model that accurately characterizes this dependence. In the appendices, we describe the extended LRG samples observed during SV.
This paper has not been read by Pith yet.
Forward citations
Cited by 22 Pith papers
-
First detection of the moving lens effect with ACT and DESI LS
First observational detection of the moving lens effect via cross-correlation of ACT CMB temperature with DESI galaxies, yielding amplitude b_ML = 1.24 ± 0.26 at 4.8σ consistent with halo-model prediction.
-
Fewer simulations, sharper covariances: Reducing mock covariance noise with Zeldovich approximation control variates
Control variates with Zeldovich mocks reduce covariance matrix variance by up to an order of magnitude on large scales in DESI-like mocks.
-
A First Observational Assessment of Cosmic Backreaction Over an Extended Redshift Range
First direct constraints on total cosmic backreaction over a significant redshift range are consistent with vanishing backreaction within 1 sigma but are too weak to exclude meaningful backreaction.
-
Measurement of the galaxy-velocity power spectrum of DESI tracers with the kinematic Sunyaev-Zeldovich effect using DESI DR2 and ACT DR6
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 DR2 Results II: Measurements of Baryon Acoustic Oscillations and Cosmological Constraints
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.
-
DESI 2024 VI: Cosmological Constraints from the Measurements of Baryon Acoustic Oscillations
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 2024 III: Baryon Acoustic Oscillations from Galaxies and Quasars
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.
-
Precision Kinematic Sunyaev--Zel'dovich Measurements Across Halo Mass and Redshift with DESI DR2 and ACT DR6: Part I. Luminous Red Galaxies
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.
-
Model-independent constraints on generalized FLRW consistency relations with bootstrap-based symbolic regression
Bootstrap-based symbolic regression on supernova and BAO data finds mild 2-4 sigma deviations from FLRW consistency relations, which if real would rule out most FLRW-based solutions to cosmological tensions.
-
Parity Violation in Galaxy Shapes: Primordial Non-Gaussianity
The parity-odd intrinsic alignment power spectrum probes the collapsed limit of the parity-odd primordial trispectrum and can tighten constraints on parity-violating PNG when bias parameters are calibrated from N-body...
-
DESI 2024 VII: Cosmological Constraints from the Full-Shape Modeling of Clustering Measurements
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 ma...
-
DESI 2024 V: Full-Shape Galaxy Clustering from Galaxies and Quasars
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.
-
Taming Additive Systematics via Redshift-Bin-Optimized Star-Galaxy Separation
Redshift-bin-optimized color cuts using unWISE photometry reduce stellar contamination in the DES Y3 MagLim lens sample by 1.3-5.5% varying across bins and footprint.
-
Cosmological Impact of Redshift-Dependent Type Ia Supernovae Calibration
A phenomenological redshift-dependent SNIa magnitude correction shows no evidence in ΛCDM but is preferred at 4.3σ with dynamical dark energy, reducing Hubble tension to 1.5σ.
-
Perturbation Dynamics and Structure Formation in Extended Proca-Nuevo Gravity
Extended Proca-Nuevo gravity modifies the background expansion via a vector field algebraic constraint but leaves the matter growth equation identical to general relativity.
-
Combined tracer analysis for DESI 2024 BAO
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.
-
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.
-
Cosmological constraints from the DESI DR1 Bispectrum Full-Shape and DR2 BAO
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 m...
-
DESI Data Release 2 ELGs: Property-dependent subsamples, imaging systematics, and clustering
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.
-
Testing Scale-Dependent Modified Gravity with DESI DR1
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.
-
Revisiting the Hubble tension problem in the framework of holographic dark energy
HDE models with future event horizon IR cutoff partially ease the Hubble tension while Hubble-scale cutoffs do not, consistent across six models and multiple BAO/SN/CMB combinations.
-
MUltiplexed Survey Telescope (MUST) Science White Paper I: Overview of Large-Scale Structure Cosmology in the Era of Stage-V Spectroscopic Surveys
MUST is a planned 6.5m Stage-V spectroscopic survey telescope targeting 100M+ galaxies and quasars to z~5.5 for large-scale structure cosmology studies.
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.