Mustapha Ishak
A5091275608- Cosmology and Gravitation Theories
- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Black Holes and Theoretical Physics
- Relativity and Gravitational Theory
- Geophysics and Gravity Measurements
- Stellar, planetary, and galactic studies
- Adaptive optics and wavefront sensing
- Dark Matter and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Scientific Research and Discoveries
- Radio Astronomy Observations and Technology
- Astrophysics and Cosmic Phenomena
- Solar and Space Plasma Dynamics
- Pulsars and Gravitational Waves Research
- CCD and CMOS Imaging Sensors
- Computational Physics and Python Applications
- Astronomical Observations and Instrumentation
- Statistical and numerical algorithms
- Advanced Differential Geometry Research
- Particle physics theoretical and experimental studies
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Superconducting and THz Device Technology
- Advanced Mathematical Theories and Applications
The University of Texas at Dallas
2015-2024
Institut de Recherche Dupuy de Lôme
2023
Southern Methodist University
2023
Institute of Theoretical Physics
2009
Princeton University
2003-2006
Queen's University
1999-2002
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...
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...
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 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...
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 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 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 In preparation for the next generation of galaxy redshift surveys, and in particular year-one data release from Dark Energy Spectroscopic Instrument (DESI), we investigate consistency a variety effective field theory models that describe galaxy-galaxy power spectra space into quasi-linear regime using 1-loop perturbation theory. These are employed pipelines velocileptors , PyBird Folps ν . While these have been validated independently, detailed comparison with consistent choices has...
Abstract The Dark Energy Spectroscopic Instrument (DESI) will provide unprecedented information about the large-scale structure of our Universe. In this work, we study robustness theoretical modelling power spectrum Folps , a novel effective field theory-based package for evaluating redshift space in presence massive neutrinos. We perform validation by fitting AbacusSummit high-accuracy N -body simulations Luminous Red Galaxies, Emission Line Galaxies and Quasar tracers, calibrated to...
Correlations between intrinsic shear and the density field on large scales, a potentially important contaminant for cosmic surveys, have been robustly detected at low redshifts with bright galaxies in Sloan Digital Sky Survey (SDSS) data. Here we present more detailed characterization of this effect, which can cause anticorrelations gravitational lensing ellipticity (GI correlations). This measurement uses 36 278 luminous red (LRGs) from SDSS spectroscopic sample 0.15 < z 0.35, split by...
If general relativity is the correct theory of physics on large scales, then there a differential equation that relates Hubble expansion function, inferred from measurements angular diameter distance and luminosity distance, to growth rate scale structure. For dark energy fluid without couplings or an unusual sound speed, deviations this consistency relationship could be signature modified gravity cosmological scales. We propose procedure based relation in order distinguish between some...
We study the effect of cosmological constant $\ensuremath{\Lambda}$ on bending light by a concentrated spherically symmetric mass. Contrarily to previous claims, we show that, when Schwarzschild-de Sitter geometry is taken into account, does indeed contribute bending.
The power spectrum of weak lensing shear caused by large-scale structure is an emerging tool for precision cosmology, in particular measuring the effects dark energy on growth at low redshift. One potential source systematic error intrinsic alignments ellipticities neighbouring galaxies (II correlation) that could mimic correlations due to lensing. A related possibility pointed out Hirata and Seljak (2004) correlation between density field responsible gravitational (GI correlation). We...
Abstract We describe the simulated sky survey underlying second data challenge (DC2) carried out in preparation for analysis of Vera C. Rubin Observatory Legacy Survey Space and Time (LSST) by LSST Dark Energy Science Collaboration (LSST DESC). Significant connections across multiple science domains will be a hallmark LSST; DC2 program represents unique modeling effort that stresses this interconnectivity way has not been attempted before. This encompasses full end-to-end approach: starting...