Biprateep Dey
A5080419920- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- CCD and CMOS Imaging Sensors
- Radio Astronomy Observations and Technology
- Adaptive optics and wavefront sensing
- Astrophysics and Cosmic Phenomena
- Remote Sensing in Agriculture
- Pulsars and Gravitational Waves Research
- Impact of Light on Environment and Health
- Photocathodes and Microchannel Plates
- Geophysics and Gravity Measurements
- Infrared Target Detection Methodologies
- Explainable Artificial Intelligence (XAI)
- Nuclear reactor physics and engineering
- Particle Detector Development and Performance
- Atmospheric Ozone and Climate
- Dark Matter and Cosmic Phenomena
- Spectroscopy and Chemometric Analyses
- Gaussian Processes and Bayesian Inference
- Spacecraft and Cryogenic Technologies
University of Pittsburgh
2020-2025
Netherlands Institute for Radio Astronomy
2024
Pittsburgh Supercomputing Center
2020-2023
National Institute of Science Education and Research
2018-2020
University of Alberta
2019
The Dark Energy Spectroscopic Instrument (DESI) has embarked on an ambitious five-year survey to explore the nature of dark energy with spectroscopy 40 million galaxies and quasars. DESI will determine precise redshifts employ Baryon Acoustic Oscillation method measure distances from nearby universe z > 3.5, as well growth structure probe potential modifications general relativity. In this paper we describe significant instrumentation developed for survey. new includes a wide-field, 3.2-deg...
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...
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). scientific program for DESI evaluated during month Survey Validation (SV) campaign before beginning full operations. This produced deep spectra tens thousands objects from each stellar (MWS), bright galaxy (BGS), luminous red (LRG), emission line (ELG), and quasar...
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 The Dark Energy Spectroscopic Instrument (DESI) completed its 5 month Survey Validation in 2021 May. Spectra of stellar and extragalactic targets from constitute the first major data sample DESI survey. This paper describes public release those spectra, catalogs derived properties, intermediate products. In total, includes good-quality spectral information 466,447 objects targeted as part Milky Way Survey, 428,758 Bright Galaxy 227,318 Luminous Red sample, 437,664 Emission Line...
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 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...
The Dark Energy Spectroscopic Instrument (DESI) completed its five-month Survey Validation in May 2021. Spectra of stellar and extragalactic targets from constitute the first major data sample DESI survey. This paper describes public release those spectra, catalogs derived properties, intermediate products. In total, includes good-quality spectral information 466,447 objects targeted as part Milky Way Survey, 428,758 Bright Galaxy 227,318 Luminous Red sample, 437,664 Emission Line 76,079...
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 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 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...
Baryon acoustic oscillation data from the first year of Dark Energy Spectroscopic Instrument (DESI) provide near percent-level precision cosmic distances in seven bins over redshift range $z=0.1$-$4.2$. We use this data, together with other distance probes, to constrain expansion history using some well-motivated physical classes dark energy. In particular, we explore three physics-focused behaviors energy equation state and density perspectives: thawing class (matching many simple...
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 this paper, we present the estimation of systematics related to halo occupation distribution (HOD) modeling in baryon acoustic oscillations (BAO) distance measurement Dark Energy Spectroscopic Instrument (DESI) 2024 analysis. This paper focuses on study HOD for luminous red galaxies (LRG). We consider three different models LRGs, including base 5-parameter vanilla model and two extensions it, that refer as baseline extended models. The is described by 5 parameters, an...
Abstract In the contemporary era of high-precision spectroscopic surveys, led by projects like DESI, there is an increasing demand for optimizing extraction cosmological information from clustering data. This work conducts a thorough comparison various methodologies modeling full shape two-point statistics in configuration space. We investigate performance both direct fits ( Full Modeling ) and parameter compression approaches ShapeFit Standard ). utilize ABACUS-SUMMIT simulations, tailored...
Abstract Dark Energy Spectroscopic Instrument (DESI) uses more than 2.4 million Emission Line Galaxies (ELGs) for 3D large-scale structure (LSS) analyses in its Data Release 1 (DR1). Such large statistics enable thorough research on systematic uncertainties. In this study, we focus spectroscopic systematics of ELGs. The redshift success rate ( f goodz ) is the relative fraction secure redshifts among all measurements. It depends observing conditions, thus introduces non-cosmological...
Abstract We use the forward modeling pipeline, Obiwan , to study imaging systematics of Luminous Red Galaxies (LRGs) targeted by Dark Energy Spectroscopic Instrument (DESI). Imaging refers false fluctuation galaxy densities due varying observing conditions and astrophysical foregrounds corresponding surveys from which DESI LRG target galaxies are selected. update we previously developed simulate optical images used data, further WISE in infrared. This addition allows simulating LRGs sample,...
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...
The Dark Energy Spectroscopic Instrument (DESI) was designed to conduct a survey covering 14,000 deg$^2$ over five years constrain the cosmic expansion history through precise measurements of Baryon Acoustic Oscillations (BAO). scientific program for DESI evaluated during month Survey Validation (SV) campaign before beginning full operations. This produced deep spectra tens thousands objects from each stellar (MWS), bright galaxy (BGS), luminous red (LRG), emission line (ELG), and quasar...