N. G. Karaçaylı
A5053070548- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Radio Astronomy Observations and Technology
- Scientific Research and Discoveries
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- Stellar, planetary, and galactic studies
- CCD and CMOS Imaging Sensors
- Statistical and numerical algorithms
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Remote Sensing in Agriculture
- Remote Sensing and LiDAR Applications
- Calibration and Measurement Techniques
- Dark Matter and Cosmic Phenomena
- Advanced Measurement and Metrology Techniques
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Satellite Image Processing and Photogrammetry
- Forest Biomass Utilization and Management
- Forest ecology and management
- Regional Economic and Spatial Analysis
- Astrophysics and Star Formation Studies
- Image and Signal Denoising Methods
- Neutrino Physics Research
State Library of Ohio
2024-2025
The Ohio State University
2022-2025
Yale University
2019-2021
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 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 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 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 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 Baryon Acoustic Oscillations can be measured with sub-percent precision above redshift two the Lyman- α (Ly ) forest auto-correlation and its cross-correlation quasar positions. This is one of key goals Dark Energy Spectroscopic Instrument (DESI) which started main survey in May 2021. We present this paper a study contaminants to Ly are mainly caused by correlated signals introduced spectroscopic data processing pipeline as well astrophysical due foreground absorption intergalactic...
We present an effective field theory (EFT) approach to extract fundamental cosmological parameters from the Lyman-alpha forest flux fluctuations as alternative standard simulation-based techniques. As a first application, we reanalyze publicly available one-dimensional power spectrum data Sloan Digital Sky Survey. Our analysis relies on informative priors EFT that combination of public hydrodynamic simulation and emulator data. Assuming concordance model, our one-parameter yields 2%...
ABSTRACT We present the one-dimensional Ly α forest power spectrum measurement using first data provided by Dark Energy Spectroscopic Instrument (DESI). The sample comprises 26 330 quasar spectra, at redshift z &gt; 2.1, contained in DESI Early Data Release and 2 months of main survey. employ a Fast Fourier Transform (FFT) estimator compare resulting to an alternative likelihood-based method companion paper. investigate methodological instrumental contaminants associated with new...
Abstract Broad absorption line quasars (BALs) exhibit blueshifted relative to a number of their prominent broad emission features. These features can contribute quasar redshift errors and add the Lyman- α (Ly ) forest that is unrelated large-scale structure. We present detailed analysis impact BALs on Baryon Acoustic Oscillation (BAO) results with Lyα from first year data Dark Energy Spectroscopic Instrument (DESI). The baseline strategy for mask all pixels associated BAL fall within...
Abstract We present the first measurements of Lyman- α (Ly ) forest correlations using early data from Dark Energy Spectroscopic Instrument (DESI). measure auto-correlation Ly absorption 88 509 quasars at z > 2, and its cross-correlation with a further 147 899 tracer ≳ 1.77. Then, we fit these 13-parameter model based on linear perturbation theory find that it provides good description across broad range scales. detect BAO peak signal-to-noise ratio 3.8 σ , show our auto-...
ABSTRACT We present and validate the catalogue of Lyman-α forest fluctuations for 3D analyses using Early Data Release (EDR) from Dark Energy Spectroscopic Instrument (DESI) survey. used 88 511 quasars collected DESI Survey Validation (SV) data first two months main survey (M2). several improvements to method extract absorption performed in previous Sloan Digital Sky (SDSS). In particular, we modify weighting scheme show that it can improve precision correlation function measurement by more...
We present the measurements and cosmological implications of galaxy two-point clustering using over 4.7 million unique quasar redshifts in range $0.1<z<2.1$ divided into six redshift bins a $\sim 7,500$ square degree footprint, from first year observations with Dark Energy Spectroscopic Instrument (DESI Data Release 1). By fitting full power spectrum, we extend previous DESI DR1 baryon acoustic oscillation (BAO) to include redshift-space distortions signals matter-radiation equality scale....
We measure the 1D Ly$\,\alpha$ power spectrum $P_\mathrm{1D}$ from Keck Observatory Database of Ionized Absorption toward Quasars (KODIAQ), The Spectral Quasar (SQUAD) and XQ-100 quasars using optimal quadratic estimator. combine KODIAQ SQUAD at level, but perform a separate estimation to control its large resolution corrections in check. Our final analysis measures scales $k<0.1\,$s$\,$km$^{-1}$ between redshifts $z=$ 2.0 -- 4.6 538 quasars. This sample provides largest number...
Abstract The first year of data from the Dark Energy Spectroscopic Instrument (DESI) contains largest set Lyman- α (Ly ) forest spectra ever observed. This data, collected in DESI Data Release 1 (DR1) sample, has been used to measure Baryon Acoustic Oscillation (BAO) feature at redshift z = 2.33. In this work, we use a 150 synthetic realizations DR1 validate 2024 Ly BAO measurement presented [1]. sets are based on Gaussian random fields using log-normal approximation. We produce realistic...
Abstract Synthetic data sets are used in cosmology to test analysis procedures, verify that systematic errors well understood and demonstrate measurements unbiased. In this work we describe the methods generate synthetic datasets of Lyman-α quasar spectra aimed for studies with Dark Energy Spectroscopic Instrument (DESI). particular, focus on demonstrating our simulations reproduces important features real samples, making them suitable be DESI place limits effects Baryon Acoustic...
Abstract The Dark Energy Spectroscopic Instrument (DESI) will measure millions of quasar spectra by the end its 5 year survey. Quasar redshift errors impact shape Lyman- α forest correlation functions, which can affect cosmological analyses and therefore interpretations. Using data from DESI Early Data Release first two months main survey, we systematic error an offset in cross-correlation with quasars. We find evidence for a dependent bias causing redshifts to be underestimated increasing...
We present baryon acoustic oscillation (BAO) measurements from more than 14 million galaxies and quasars drawn the Dark Energy Spectroscopic Instrument (DESI) Data Release 2 (DR2), based on three years of operation. For cosmology inference, these galaxy are combined with DESI Lyman-$\alpha$ forest BAO results presented in a companion paper. The DR2 consistent DR1 SDSS, their distance-redshift relationship matches those recent compilations supernovae (SNe) over same redshift range. well...
We present the Baryon Acoustic Oscillation (BAO) measurements with Lyman-alpha (LyA) forest from second data release (DR2) of Dark Energy Spectroscopic Instrument (DESI) survey. Our BAO include both auto-correlation LyA absorption observed in spectra high-redshift quasars and cross-correlation quasar positions. The total sample size is approximately a factor two larger than DR1 dataset, over 820,000 positions 1.2 million quasars. describe several significant improvements to our analysis this...
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...
Synthetic data sets are used in cosmology to test analysis procedures, verify that systematic errors well understood and demonstrate measurements unbiased. In this work we describe the methods generate synthetic datasets of Lyman-$\alpha$ quasar spectra aimed for studies with Dark Energy Spectroscopic Instrument (DESI). particular, focus on demonstrating our simulations reproduces important features real samples, making them suitable be DESI place limits effects Baryon Acoustic Oscillations...
Abstract We present the Ly α Continuum Analysis Network (LyCAN), a convolutional neural network that predicts unabsorbed quasar continuum within rest-frame wavelength range of 1040–1600 Å based on red side emission line (1216–1600 Å). developed synthetic spectra Gaussian mixture model representation nonnegative matrix factorization (NMF) coefficients. These coefficients were derived from high-resolution, low-redshift ( z < 0.2) Hubble Space Telescope/Cosmic Origins Spectrograph (COS)...
ABSTRACT The 1D Ly α forest flux power spectrum P1D is sensitive to scales smaller than a typical galaxy survey, and hence ties the intergalactic medium’s thermal state, suppression from neutrino masses, new dark matter models. It has emerged as competitive framework study physics, but also come with various challenges systematic errors in analysis. In this work, we revisit optimal quadratic estimator for P1D, which robust against relevant problems such pixel masking, time evolution within...
The abundance, temperature, and clustering of metals in the intergalactic medium are important parameters for understanding their cosmic evolution quantifying impact on cosmological analysis with Ly $\alpha$ forest. properties these systems typically measured from individual quasar spectra redward quasar's emission line, yet that approach may provide biased results due to selection effects. We present an alternative measure unbiased manner two-point statistics commonly employed quantify...