Lado Samushia
A5041542317- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Dark Matter and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Scientific Research and Discoveries
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Statistical and numerical algorithms
- Solar and Space Plasma Dynamics
- Adaptive optics and wavefront sensing
- Remote Sensing in Agriculture
- Astronomical Observations and Instrumentation
- Advanced Statistical Methods and Models
- Blind Source Separation Techniques
- Computational Physics and Python Applications
- Relativity and Gravitational Theory
- Advanced Adaptive Filtering Techniques
- Spectroscopy and Chemometric Analyses
- Particle Detector Development and Performance
- Advanced Electrical Measurement Techniques
- Stochastic processes and financial applications
Ilia State University
2014-2025
Kansas State University
2016-2025
Abastumani Astrophysical Observatory
2014-2024
Kansas State Department of Education
2019
University of Portsmouth
2010-2018
Brookhaven National Laboratory
2017
We present cosmological results from the final galaxy clustering data set of Baryon Oscillation Spectroscopic Survey, part Sloan Digital Sky Survey III. Our combined sample comprises 1.2 million massive galaxies over an effective area 9329 deg^2 and volume 18.7 Gpc^3, divided into three partially overlapping redshift slices centred at redshifts 0.38, 0.51, 0.61. measure angular diameter distance DM Hubble parameter H baryon acoustic oscillation (BAO) method after applying reconstruction to...
We present a one per cent measurement of the cosmic distance scale from detections baryon acoustic oscillations (BAO) in clustering galaxies Baryon Oscillation Spectroscopic Survey, which is part Sloan Digital Sky Survey III. Our results come Data Release 11 (DR11) sample, containing nearly million and covering approximately 8500 square degrees redshift range 0.2 < |$z$| 0.7. also compare these with those publicly released DR9 DR10 samples. Assuming concordance Λ cold dark matter (ΛCDM)...
We create a sample of spectroscopically identified galaxies with $z < 0.2$ from the Sloan Digital Sky Survey (SDSS) Data Release 7, covering 6813 deg$^2$. Galaxies are chosen to highest mass haloes, an effective bias 1.5, allowing us construct 1000 mock galaxy catalogs (described in Paper II), which we use estimate statistical errors and test our methods. gravitational potential "reconstruct" linear density fluctuations, enhancing Baryon Acoustic Oscillation (BAO) signal measured correlation...
We present measurements of galaxy clustering from the Baryon Oscillation Spectroscopic Survey (BOSS), which is part Sloan Digital Sky III (SDSS-III). These use Data Release 9 (DR9) CMASS sample, contains 264 283 massive galaxies covering 3275 square degrees with an effective redshift z = 0.57 and range 0.43 < 0.7. Assuming a concordance ΛCDM cosmological model, this sample covers volume 2.2 Gpc3, represents largest Universe ever surveyed at density, . measure angle-averaged correlation...
We derive constraints on cosmological parameters and tests of dark energy models from the combination baryon acoustic oscillation (BAO) measurements with cosmic microwave background (CMB) Type Ia supernova (SN) data. take advantage high-precision BAO galaxy clustering Ly-alpha forest (LyaF) in BOSS survey SDSS-III. data alone yield a high confidence detection energy, CMB angular scale they further imply nearly flat universe. Combining SN into an "inverse distance ladder" yields 1.7%...
The Baryon Oscillation Spectroscopic Survey (BOSS), part of the Sloan Digital Sky (SDSS) III project, has provided largest survey galaxy redshifts available to date, in terms both number measured by a single survey, and effective cosmological volume covered. Key analysing clustering these data provide measurements is understanding detailed properties this sample. Potential issues include variations target catalogue caused changes either targeting algorithm or used, pattern spectroscopic...
We analyze the anisotropic clustering of massive galaxies from Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic (BOSS) Data Release 9 (DR9) sample, which consists 264,283 in redshift range 0.43 < z 0.7 spanning 3,275 square degrees. Both peculiar velocities and errors assumed redshift-distance relation ("Alcock-Paczynski effect") generate correlations between amplitude orientation with respect to line-of-sight. Together sharp baryon acoustic oscillation (BAO) standard ruler, our...
We analyse the anisotropic clustering of Baryon Oscillation Spectroscopic Survey (BOSS) CMASS Data Release 11 (DR11) sample, which consists $690\,827$ galaxies in redshift range $0.43 < z 0.7$ and has a sky coverage $8\,498\,\text{deg}^2$. perform our analysis Fourier space using power spectrum estimator suggested by Yamamoto et al. (2006). measure multipole spectra self-consistent manner for first time sense that we provide proper way to treat survey window function integral constraint,...
We present a fast method of producing mock galaxy catalogues that can be used to compute covariance matrices large-scale clustering measurements and test the methods analysis. Our populates 2nd-order Lagrangian Perturbation Theory (2LPT) matter field, where we calibrate masses dark halos by detailed comparisons with N-body simulations. demonstrate is recovered at ~10 per cent accuracy. populate galaxies using Halo Occupation Distribution (HOD) prescription, which has been calibrated...
The simplest theory describing large-scale redshift-space distortions (RSD), based on linear and distant galaxies, depends the growth of cosmological structure, suggesting that strong tests General Relativity can be constructed from galaxy surveys. As data sets become larger expected constraints more precise, extent to which RSD follow simple needs assessed in order we do not introduce systematic errors into by introducing inaccurate simplifying assumptions. We study impact sample geometry,...
We use the observed anisotropic clustering of galaxies in Baryon Oscillation Spectroscopic Survey Data Release 11 CMASS sample to measure linear growth rate structure, Hubble expansion and comoving distance scale. Our covers 8498 deg2 encloses an effective volume 6 Gpc3 at redshift |$\bar{z} = 0.57$|. find fσ8 0.441 ± 0.044, H 93.1 3.0 km s−1 Mpc−1 DA 1380 23 Mpc when fitting simultaneously. When we fix background one predicted by spatially flat Λ cold dark matter (ΛCDM) model agreement...
We analyse the density field of galaxies observed by Sloan Digital Sky Survey (SDSS)-III Baryon Oscillation Spectroscopic (BOSS) included in SDSS Data Release Nine (DR9). DR9 includes spectroscopic redshifts for over 400 000 spread a footprint 3275 deg2. identify, characterize and mitigate impact sources systematic uncertainty on large-scale clustering measurements, both angular moments redshift-space correlation function, ξℓ(s), spherically averaged power spectrum, P(k), order to ensure...
We measure Redshift-Space Distortions (RSD) in the two-point correlation function of a sample $63,163$ spectroscopically identified galaxies with $z < 0.2$, an epoch where there are currently only limited measurements, from Sloan Digital Sky Survey (SDSS) Data Release 7 Main Galaxy Sample. Our sample, which we denote MGS, covers 6,813 deg$^2$ effective redshift $z_{eff}=0.15$ and is described our companion paper (Paper I), concentrates on BAO measurements. In order to validate fitting...
We present improved methodology for including covariance matrices in the error budget of Baryon Oscillation Spectroscopic Survey (BOSS) galaxy clustering measurements, revisiting Data Release 9 (DR9) analyses, and describing a method that is used DR10/11 analyses presented companion papers. The precise analysis adopted becoming increasingly important, due to precision BOSS can now reach: even using as many 600 mock catalogues estimate two-point measurements still lead an increase errors ∼20...
We present measurements of the angular diameter distance to and Hubble parameter at z=0.57 from measurement baryon acoustic peak in correlation galaxies Sloan Digital Sky Survey III Baryon Oscillation Spectroscopic Survey. Our analysis is based on a sample Data Release 9 264,283 over 3275 square degrees redshift range 0.43<z<0.70. use two different methods provide robust position across along line sight order measure cosmological scale. find D_A(0.57) = 1408 +/- 45 Mpc H(0.57) 92.9 7.8...
We measure and analyse the clustering of Baryon Oscillation Spectroscopic Survey (BOSS) relative to line-of-sight (LOS), for LOWZ CMASS galaxy samples drawn from final Data Release 12 (DR12). The sample contains 361\,762 galaxies with an effective redshift $z_{\rm lowz}=0.32$, 777\,202 cmass}=0.57$. From power spectrum monopole quadrupole moments around LOS, we growth structure parameter $f$ times amplitude dark matter density fluctuations $\sigma_8$ by modeling Redshift-Space Distortion...
We present a study of the clustering and halo occupation distribution Baryon Oscillation Spectroscopic Survey (BOSS) CMASS galaxies in redshift range 0.43 < z 0.7 drawn from Final SDSS-III Data Release. compare BOSS results with predictions abundance matching (HAM) model that assigns to dark matter haloes selected large BigMultiDark N-body simulation flat Λ cold Planck cosmology. observational data simulated ones on light cone constructed 20 subsequent outputs simulation. Observational...
We explore the cosmological implications of anisotropic clustering measurements in configuration space final galaxy samples from Data Release 12 SDSS-III Baryon Oscillation Spectroscopic Survey. implement a new detailed modelling effects non-linearities, bias and redshift-space distortions that can be used to extract unbiased information our for scales $s \gtrsim 20\,h^{-1}{\rm Mpc}$. combined BOSS with latest cosmic microwave background (CMB) observations Type Ia supernovae found no...
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 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...
We use the joint measurement of geometry and growth from anisotropic galaxy clustering in Baryon Oscillation Spectroscopic Survey (BOSS) Data Release 9 (DR9) CMASS sample reported by Reid et al. to constrain dark energy (DE) properties possible deviations General Relativity (GR).Assuming GR taking a prior on linear matter power spectrum at high redshift cosmic microwave background (CMB), DR9 galaxies alone constrains Ω m = 0.308 ± 0.022 100Ω k 5.9 4.8 for w -1, or -0.91 0.12 0.When combined...
We explore the cosmological implications of angle-averaged correlation function, ξ(s), and clustering wedges, ξ⊥(s) ξ∥(s), LOWZ CMASS galaxy samples from Data Releases 10 11 Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation standard Λ cold dark matter model. The combination information our measurements with recent data cosmic microwave background is sufficient to constrain curvature Universe Ωk = 0.0010 ±...
We analyze the density field of 264,283 galaxies observed by Sloan Digital Sky Survey (SDSS)-III Baryon Oscillation Spectroscopic (BOSS) and included in SDSS data release nine (DR9). In total, DR9 BOSS includes spectroscopic redshifts for over 400,000 spread a footprint more than 3,000 deg^2. measure power spectrum these with 0.43 < z 0.7 order to constrain amount local non-Gaussianity, f_NL,local, primordial field, paying particular attention impact systematic uncertainties. The galaxy is...
With the largest spectroscopic galaxy survey volume drawn from SDSS-III Baryon Oscillation Spectroscopic Survey (BOSS), we can extract cosmological constraints measurements of redshift and geometric distortions at quasi-linear scales (e.g. above 50 h−1 Mpc). We analyse broad-range shape monopole quadrupole correlation functions BOSS Data Release 12 (DR12) CMASS sample, effective z = 0.59, to obtain on Hubble expansion rate H(z), angular- diameter distance DA(z), normalized growth f(z)σ8(z),...
We investigate the cosmological implications of latest growth structure measurement from Baryon Oscillation Spectroscopic Survey (BOSS) CMASS Data Release 11 with particular focus on sum neutrino masses, ∑mν. examine robustness constraints baryon acoustic oscillation (BAO) scale, Alcock–Paczynski effect and redshift-space distortions (DV/rs, FAP, fσ8) Beutler et al., when introducing a mass in power spectrum template. then discuss how relaxes discrepancies between cosmic microwave background...