Martin Landriau
A5038903058- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Radio Astronomy Observations and Technology
- Scientific Research and Discoveries
- CCD and CMOS Imaging Sensors
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Dark Matter and Cosmic Phenomena
- Statistical and numerical algorithms
- Particle Detector Development and Performance
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Impact of Light on Environment and Health
- Photocathodes and Microchannel Plates
- Gaussian Processes and Bayesian Inference
- Geophysics and Gravity Measurements
- Advanced Statistical Methods and Models
- Astro and Planetary Science
- Remote Sensing in Agriculture
- Superconducting and THz Device Technology
Lawrence Berkeley National Laboratory
2016-2025
The University of Texas at Austin
2014-2021
Max Planck Institute for Extraterrestrial Physics
2011-2021
University of California, Berkeley
2020
GANIL
2003-2019
McDonald's (United States)
2018
Stuttgart Observatory
2012
Ludwig-Maximilians-Universität München
2012
Optica
2012
Max Planck Society
2012
Abstract The DESI Legacy Imaging Surveys ( http://legacysurvey.org/ ) are a combination of three public projects (the Dark Energy Camera Survey, the Beijing–Arizona Sky and Mayall z -band Survey) that will jointly image ≈14,000 deg 2 extragalactic sky visible from northern hemisphere in optical bands g , r using telescopes at Kitt Peak National Observatory Cerro Tololo Inter-American Observatory. combined survey footprint is split into two contiguous areas by Galactic plane. imaging...
Abstract Over the next 5 yr, Dark Energy Spectroscopic Instrument (DESI) will use 10 spectrographs with 5000 fibers on 4 m Mayall Telescope at Kitt Peak National Observatory to conduct first Stage IV dark energy galaxy survey. At z < 0.6, DESI Bright Galaxy Survey (BGS) produce most detailed map of universe during dark-energy-dominated epoch redshifts >10 million galaxies spanning 14,000 deg 2 . In this work, we present and validate final BGS target selection survey design. From Legacy...
Abstract The Dark Energy Spectroscopic Instrument (DESI) is carrying out a five-year survey that aims to measure the redshifts of tens millions galaxies and quasars, including 8 million luminous red (LRGs) in redshift range 0.4 < z ≲ 1.0. Here we present selection DESI LRG sample assess its spectroscopic performance using data from Survey Validation (SV) first two months Main Survey. sample, selected g , r W 1 photometry Legacy Imaging Surveys, highly robust against imaging systematics....
Abstract We describe the spectroscopic data processing pipeline of Dark Energy Spectroscopic Instrument (DESI), which is conducting a redshift survey about 40 million galaxies and quasars using purpose-built instrument on 4 m Mayall Telescope at Kitt Peak National Observatory. The main goal DESI to measure with unprecedented precision expansion history universe baryon acoustic oscillation technique growth rate structure space distortions. Ten spectrographs three cameras each disperse light...
Abstract The Hobby–Eberly Telescope (HET) Dark Energy Experiment (HETDEX) is undertaking a blind wide-field low-resolution spectroscopic survey of 540 deg 2 sky to identify and derive redshifts for million Ly α -emitting galaxies in the redshift range 1.9 < z 3.5. ultimate goal measure expansion rate universe at this epoch, sharply constrain cosmological parameters thus nature dark energy. A major multiyear Wide-Field Upgrade (WFU) HET was completed 2016 that substantially increased field...
Abstract The Dark Energy Spectroscopic Instrument (DESI) survey will measure large-scale structures using quasars as direct tracers of dark matter in the redshift range 0.9 < z 2.1 and Ly α forests quasar spectra at > 2.1. We present several methods to select candidate for DESI, input photometric imaging three optical bands ( g , r ) from DESI Legacy Imaging Surveys two infrared (W1, W2) Wide-field Infrared Survey Explorer. These were extensively tested during Validation DESI. In this...
Abstract A system of 5020 robotic fiber positioners was installed in 2019 on the Mayall Telescope, at Kitt Peak National Observatory. The robots automatically retarget their optical fibers every 10–20 minutes, each to a precision several microns, with reconfiguration time fewer than 2 minutes. Over next 5 yr, they will enable newly constructed Dark Energy Spectroscopic Instrument (DESI) measure spectra 35 million galaxies and quasars. DESI produce largest 3D map universe date expansion...
Abstract The Dark Energy Spectroscopic Instrument (DESI) will precisely constrain cosmic expansion and the growth of structure by collecting ∼40 million extragalactic redshifts across ∼80% history one-third sky. Emission Line galaxy (ELG) sample, which comprise about all DESI tracers, be used to probe universe over 0.6 < z 1.6 range, including 1.1 is expected provide tightest constraints. We present target selection for Survey Validation (SV) Main ELG samples, relies on imaging Legacy...
In 2021 May, the Dark Energy Spectroscopic Instrument (DESI) began a 5 yr survey of approximately 50 million total extragalactic and Galactic targets. The primary DESI dark-time targets are emission line galaxies (ELGs), luminous red (LRGs) quasars (QSOs). bright time, will focus on two surveys known as Bright Galaxy Survey (BGS) Milky Way (MWS). also observes selection "secondary" for bespoke science goals. This paper gives an overview publicly available pipeline (desitarget) used to...
Abstract We present the measurement of Baryon Acoustic Oscillations (BAO) from Lyman- α (Ly ) forest high-redshift quasars with first-year dataset Dark Energy Spectroscopic Instrument (DESI). Our analysis uses over 420 000 Ly spectra and their correlation spatial distribution more than 700 quasars. An essential facet this work is development a new methodology on blinded dataset. conducted rigorous tests using synthetic data to ensure reliability our findings before unblinding. Additionally,...
We describe the Milky Way Survey (MWS) that will be undertaken with Dark Energy Spectroscopic Instrument (DESI) on Mayall 4m telescope at Kitt Peak National Observatory. Over next 5 yr DESI MWS observe approximately seven million stars Galactic latitudes |b|>20 degrees, an inclusive target selection scheme focused thick disk and stellar halo. also include several high-completeness samples of rare types, including white dwarfs, low-mass within 100pc Sun, horizontal branch stars. summarize...
Abstract The Dark Energy Spectroscopic Instrument (DESI) survey is a spectroscopic of tens millions galaxies at 0 < z 3.5 covering 14,000 sq. deg. the sky. In its first 1.1 yr operations, it has observed more than 14 million and 4 stars. We describe processes that govern DESI’s observations 15,000 fields composing survey. This includes planning each night’s in afternoon; automatic selection to observe during night; real-time assessment field completeness on basis observing conditions...
Abstract A key component of the Dark Energy Spectroscopic Instrument (DESI) survey validation (SV) is a detailed visual inspection (VI) optical spectroscopic data to quantify metrics. In this paper we present results from VI quasar using deep coadded SV spectra. We show that majority (≈70%) main-survey targets are spectroscopically confirmed as quasars, with ≈16% galaxies, ≈6% stars, and ≈8% low-quality spectra lacking reliable features. nonnegligible fraction quasars misidentified by...
Abstract The Dark Energy Spectroscopic Instrument (DESI) Survey has obtained a set of spectroscopic measurements galaxies to validate the final survey design and target selections. To assist in these tasks, we visually inspect DESI spectra approximately 2500 bright galaxies, 3500 luminous red (LRGs), 10,000 emission-line (ELGs) obtain robust redshift identifications. We then utilize inspected information characterize performance operation. Based on visual inspection (VI) catalogs, our...
We present the DESI 2024 galaxy and quasar baryon acoustic oscillations (BAO) measurements using over 5.7 million unique redshifts in range 0.1<z<2.1. Divided by tracer type, we utilize 300,017 galaxies from magnitude-limited Bright Galaxy Survey with 0.1<z<0.4, 2,138,600 Luminous Red Galaxies 0.4<z<1.1, 2,432,022 Emission Line 0.8<z<1.6, 856,652 quasars 0.8<z<2.1, a ~7,500 square degree footprint. The analysis was blinded at catalog-level to avoid confirmation bias. All fiducial choices of...
Abstract The Dark Energy Spectroscopic Instrument (DESI) is currently measuring the spectra of 40 million galaxies and quasars, largest such survey ever made to probe nature cosmological dark energy. 4 m Mayall telescope at Kitt Peak National Observatory has been adapted for DESI, including construction a 3.°2 diameter prime focus corrector that focuses astronomical light onto 0.8 focal surface with excellent image quality over DESI bandpass 360–980 nm. wide-field includes six lenses, as...
Abstract We implement Crossing Statistics to reconstruct in a model-agnostic manner the expansion history of universe and properties dark energy, using DESI Data Release 1 (DR1) BAO data combination with one three different supernova compilations (PantheonPlus, Union3, DES-SN5YR) Planck CMB observations. Our results hint towards an evolving emergent energy behaviour, negligible presence at z ≳ 1, varying significance depending on sets combined. In all these reconstructions, cosmological...
ABSTRACT We present the first comprehensive halo occupation distribution (HOD) analysis of Dark Energy Spectroscopic Instrument (DESI) One-Percent Survey luminous red galaxy (LRG) and Quasi Stellar Object (QSO) samples. constrain HOD each sample test possible extensions by fitting redshift-space 2-point correlation functions in 0.15 &lt; r 32 h−1 Mpc a set fiducial redshift bins. use AbacusSummit cubic boxes at Planck 2018 cosmology as model templates forward clustering with AbacusHOD...
ABSTRACT The 1D power spectrum P1D of the Ly α forest provides important information about cosmological and astrophysical parameters, including constraints on warm dark matter models, sum masses three neutrino species, thermal state intergalactic medium. We present first measurement with quadratic maximum likelihood estimator (QMLE) from Dark Energy Spectroscopic Instrument (DESI) survey early data sample. This sample 54 600 quasars is already comparable in size to largest previous studies,...
ABSTRACT This paper provides a comprehensive overview of how fitting baryon acoustic oscillations (BAO) is carried out within the upcoming Dark Energy Spectroscopic Instrument’s (DESI) 2024 results using its DR1 data set, and associated systematic error budget from theory modelling BAO. We derive new showing non-linearities in clustering galaxies can cause potential biases measurements isotropic ($\alpha _{\mathrm{iso}}$) anisotropic _{\mathrm{ap}}$) BAO distance scales, these be effectively...
Abstract Changing-look active galactic nuclei (CL AGNs) can be generally confirmed by the emergence (turn-on) or disappearance (turn-off) of broad emission lines (BELs), associated with a transient timescale (about 100 ∼ 5000 days) that is much shorter than predicted traditional accretion disk models. We carry out systematic CL AGN search crossmatching spectra coming from Dark Energy Spectroscopic Instrument and Sloan Digital Sky Survey. Following previous studies, we identify AGNs based on...
Abstract In anticipation of forthcoming data releases current and future spectroscopic surveys, we present the validation tests analysis systematic effects within velocileptors modeling pipeline when fitting mock from AbacusSummit N-body simulations. We compare constraints obtained parameter compression methods to direct (Full-Modeling) approaches galaxy power spectra, show that ShapeFit extension traditional template method is consistent with Full-Modeling standard ΛCDM space. dependence on...
Abstract We present the technical details on how large-scale structure (LSS) catalogs are constructed from redshifts measured spectra observed by Dark Energy Spectroscopic Instrument (DESI). The LSS provide information needed to determine relative number density of DESI tracers as a function redshift and celestial coordinates and, e.g., clustering statistics. produce that weighted subsamples data, each matched `random' catalog forms an unclustered sampling probability could have those data...
Abstract Baryon acoustic oscillations (BAO) provide a robust standard ruler to measure the expansion history of Universe through galaxy clustering. Density-field reconstruction is now widely adopted procedure for increasing precision and accuracy BAO detection. With goal finding optimal settings be used in DESI 2024 analysis, we assess sensitivity post-reconstruction constraints different choices our analysis configuration, performing tests on blinded data from first year observations (DR1),...
Abstract We present the DESI 2024 galaxy and quasar baryon acoustic oscillations (BAO) measurements using over 5.7 million unique redshifts in range 0.1 < z 2.1. Divided by tracer type, we utilize 300,017 galaxies from magnitude-limited Bright Galaxy Survey with 0.4, 2,138,600 Luminous Red Galaxies 0.4 1.1, 2,432,022 Emission Line 0.8 1.6, 856,652 quasars 2.1, a ∼ 7,500 square degree footprint. The analysis was blinded at catalog-level to avoid confirmation bias. All fiducial choices of...