A5055574861- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Astrophysics and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- CCD and CMOS Imaging Sensors
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Calibration and Measurement Techniques
- Astrophysical Phenomena and Observations
- Scientific Research and Discoveries
- Radio Astronomy Observations and Technology
- Astro and Planetary Science
- Pulsars and Gravitational Waves Research
- Neutrino Physics Research
- Spectroscopy and Laser Applications
- Geophysics and Gravity Measurements
- Particle Detector Development and Performance
- Remote Sensing in Agriculture
- Semiconductor Lasers and Optical Devices
- Atmospheric Ozone and Climate
- Solar and Space Plasma Dynamics
- Astrophysics and Star Formation Studies
- Satellite Image Processing and Photogrammetry
Lawrence Berkeley National Laboratory
2014-2024
Fermi National Accelerator Laboratory
2024
Sorbonne Université
2010-2020
Centre National de la Recherche Scientifique
2010-2020
Laboratoire de Physique Nucléaire et de Hautes Énergies
2010-2020
Université Paris Cité
2010-2020
Délégation Paris 7
2018-2020
Institut National de Physique Nucléaire et de Physique des Particules
2005-2018
Orange (France)
2013
University of Oxford
2007-2008
Aims. We present cosmological constraints from a joint analysis of type Ia supernova (SN Ia) observations obtained by the SDSS-II and SNLS collaborations. The dataset includes several low-redshift samples (z< 0.1), all three seasons (0.05 <z< 0.4), years (0.2 1), it totals 740 spectroscopically confirmed supernovae with high-quality light curves.
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...
We combine high redshift Type Ia supernovae from the first 3 years of Supernova Legacy Survey (SNLS) with other supernova (SN) samples, primarily at lower redshifts, to form a high-quality joint sample 472 SNe (123 low-$z$, 93 SDSS, 242 SNLS, and 14 {\it Hubble Space Telescope}). SN data alone require cosmic acceleration >99.9% confidence, including systematic effects. For dark energy equation state parameter (assumed constant out least $z=1.4$) in flat universe, we find $w =...
We present an empirical model of Type Ia supernovae spectro-photometric evolution with time. The is built using a large data set including light-curves and spectra both nearby distant supernovae, the latter being observed by SNLS collaboration. derive average spectral sequence their main variability components color variation law. allows us to measure distance moduli in range 2500-8000 A calculable uncertainties, those arising from features. Thanks use high-redshift SNe rest-frame UV energy...
(Abridged) Precision cosmology with Type Ia supernovae (SNe Ia) makes use of the fact that SN luminosities depend on their light-curve shapes and colours. Using Supernova Legacy Survey (SNLS) other data, we show there is an additional dependence global characteristics host galaxies: events same shape colour are, average, 0.08mag (~4.0sigma) brighter in massive galaxies (presumably metal-rich) low specific star-formation rates (sSFR). SNe a sSFR also have smaller slope ("beta") between...
We report the detection of a point-like source very high energy (VHE) gamma-rays coincident within 1' Sgr A*, obtained with H.E.S.S. array Cherenkov telescopes. The exhibit power-law spectrum spectral index -2.2 +/- 0.09 0.15 and flux above 165 GeV threshold (1.82 0.22) * 10^-7 m^-2 s^-1. measured differ substantially from recent results reported in particular by CANGAROO collaboration.
We have used flux-transmission correlations in Lyα forests to measure the imprint of baryon acoustic oscillations (BAO). The study uses spectra 157 783 quasars redshift range 2.1 ≤ z 3.5 from Sloan Digital Sky Survey (SDSS) data release 12 (DR12). Besides statistical improvements on our previous studies using SDSS DR9 and DR11, we implemented numerous analysis procedure, allowing us construct a physical model correlation function investigate potential systematic errors determination BAO peak...
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...
We present cosmological results from the measurement of baryon acoustic oscillations (BAO) in galaxy, quasar and Lyman-$\alpha$ forest tracers first year observations Dark Energy Spectroscopic Instrument (DESI), to be released DESI Data Release 1. BAO provide robust measurements transverse comoving distance Hubble rate, or their combination, relative sound horizon, seven redshift bins over 6 million extragalactic objects range $0.1<z<4.2$. data alone are consistent with standard flat...
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 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...
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...
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,...
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 The Dark Energy Spectroscopic Instrument (DESI) will provide precise measurements of Baryon Acoustic Oscillations (BAO) to constrain the expansion history Universe and set stringent constraints on dark energy. Therefore, control global error budget due various systematic effects is required for DESI 2024 BAO analysis. In this work, we estimate level systematics induced in analysis assumed Halo Occupation Distribution (HOD) model Emission Line Galaxy (ELG) tracer. We make use mock...
Abstract In the era of precision cosmology, ensuring integrity data analysis through blinding techniques is paramount — a challenge particularly relevant for Dark Energy Spectroscopic Instrument (DESI). DESI represents monumental effort to map cosmic web, with goal measure redshifts tens millions galaxies and quasars. Given volume impact findings, potential confirmation bias poses significant challenge. To address this, we implement validate comprehensive blind strategy Data Release 1 (DR1),...
Abstract The large scale structure catalogs within DESI Data Release 1 (DR1) use nearly 6 million galaxies and quasars as tracers of the large-scale universe to measure expansion history with baryon acoustic oscillations growth redshift-space distortions. In order take advantage DESI's unprecedented statistical power, we must ensure that galaxy clustering measurements are unaffected by non-cosmological density fluctuations. One source spurious fluctuations comes from variation in...
We present SiFTO, a new empirical method for modeling Type Ia supernova (SN Ia) light curves by manipulating spectral template. make use of high-redshift SN data when training the model, allowing us to extend it bluer than rest-frame U. This increases utility our observations more available data. find that shape curve is described using stretch prescription, applying same at all wavelengths not an adequate description. SiFTO therefore uses generalization which applies different factors as...
The nearby supernova SN 2011fe can be observed in unprecedented detail. Therefore, it is an important test case for Type Ia (SN Ia) models, which may bring us closer to understanding the physical nature of these objects. Here, we explore how available and expected future observations used constrain explosion scenarios. We base our discussion on three-dimensional simulations a delayed detonation Chandrasekhar-mass white dwarf violent merger two dwarfs-realizations models appropriate most...