Andrej Dvornik
A5041888778- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Advanced Vision and Imaging
- Pulsars and Gravitational Waves Research
- CCD and CMOS Imaging Sensors
- Remote Sensing in Agriculture
- Statistical and numerical algorithms
- Black Holes and Theoretical Physics
- Scientific Research and Discoveries
- Statistics Education and Methodologies
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Image and Object Detection Techniques
- History and Developments in Astronomy
- demographic modeling and climate adaptation
- Geophysics and Gravity Measurements
- Algorithms and Data Compression
- Dark Matter and Cosmic Phenomena
- Spatial and Panel Data Analysis
- Spectroscopy and Chemometric Analyses
Ruhr University Bochum
2020-2024
University of Hull
2023
Leiden University
2016-2021
Leiden Observatory
2018
We present cosmological parameter constraints from a tomographic weak gravitational lensing analysis of ~450deg$^2$ imaging data the Kilo Degree Survey (KiDS). For flat $\Lambda$CDM cosmology with prior on $H_0$ that encompasses most recent direct measurements, we find $S_8\equiv\sigma_8\sqrt{\Omega_{\rm m}/0.3}=0.745\pm0.039$. This result is in good agreement other low redshift probes large scale structure, including cosmic shear results, along pre-Planck microwave background constraints. A...
We present a joint cosmological analysis of weak gravitational lensing observations from the Kilo-Degree Survey (KiDS-1000), with redshift-space galaxy clustering Baryon Oscillation Spectroscopic (BOSS), and galaxy-galaxy overlap between KiDS-1000, BOSS spectroscopic 2-degree Field Lensing (2dFLenS). This combination large-scale structure probes breaks degeneracies parameters for individual observables, resulting in constraint on growth parameter $S_8=\sigma_8 \sqrt{\Omega_{\rm m}/0.3} =...
Context . The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at VLT Telescope, specifically designed for measuring weak gravitational lensing by galaxies and large-scale structure. When completed it will consist of 1350 square degrees imaged in four filters ( ugri ). Aims Here we present fourth public data release which more than doubles area sky covered 3. We also include aperture-matched Z Y J H K s photometry from our partner VIKING on...
In Galaxy And Mass Assembly Data Release 4 (GAMA DR4), we make available our full spectroscopic redshift sample. This includes 248682 galaxy spectra, and, in combination with earlier surveys, results 330542 redshifts across five sky regions covering ~250deg^2. The density, is the highest over such a sustained area, has exceptionally high completeness (95 per cent to r_KIDS=19.65mag), and well suited for study of mergers, groups, low (z<0.25) population. DR4 32 value-added tables or...
We present a joint cosmic shear analysis of the Dark Energy Survey (DES Y3) and Kilo-Degree (KiDS-1000) in collaborative effort between two survey teams. find consistent cosmological parameter constraints DES Y3 KiDS-1000 which, when combined joint-survey analysis, constrain $S_8 = \sigma_8 \sqrt{\Omega_{\rm m}/0.3}$ with mean value $0.790^{+0.018}_{-0.014}$. The marginal is lower than maximum posteriori estimate, $S_8=0.801$, owing to skewness distribution projection effects...
We present weak lensing shear catalogues from the fourth data release of Kilo-Degree Survey, KiDS-1000, spanning 1006 square degrees deep and high-resolution imaging. Our `gold-sample' galaxies, with well-calibrated photometric redshift distributions, consists 21 million galaxies an effective number density $6.17$ per arcminute. quantify accuracy spatial, temporal, flux-dependent point-spread function (PSF) model, verifying that model meets our requirements to induce less than a $0.1\sigma$...
We present the methodology for a joint cosmological analysis of weak gravitational lensing from fourth data release ESO Kilo-Degree Survey (KiDS-1000) and galaxy clustering partially overlapping Baryon Oscillation Spectroscopic (BOSS) 2-degree Field Lensing (2dFLenS). Cross-correlations between BOSS 2dFLenS positions source ellipticities have been incorporated into analysis, necessitating development hybrid model non-linear scales that blends perturbative non-perturbative approaches, an...
We present cosmological constraints from a cosmic shear analysis of the fourth data release Kilo-Degree Survey (KiDS-1000), doubling survey area with nine-band optical and near-infrared photometry respect to previous KiDS analyses. Adopting spatially flat $\Lambda$CDM model, we find $S_8 = \sigma_8 (\Omega_{\rm m}/0.3)^{0.5} 0.759^{+0.024}_{-0.021}$ for our fiducial analysis, which is in $3\sigma$ tension prediction Planck Legacy microwave background. compare COSEBIs (Complete Orthogonal...
Verlinde proposed that the observed excess gravity in galaxies and clusters is consequence of emergent (EG). In this theory, standard gravitational laws are modified on galactic larger scales due to displacement dark energy by baryonic matter. EG gives an estimate (described as apparent matter density) terms mass distribution Hubble parameter. work, we present first test using weak lensing, within regime validity current model. Although there no direct description lensing cosmology yet, can...
We present a new sample of galaxy-scale strong gravitational-lens candidates, selected from 904 square degrees Data Release 4 the Kilo-Degree Survey (KiDS), i.e., "Lenses in Survey" (LinKS) sample. apply two Convolutional Neural Networks (ConvNets) to $\sim88\,000$ colour-magnitude luminous red galaxies yielding list 3500 strong-lens candidates. This is further down-selected via human inspection. The resulting LinKS composed 1983 rank-ordered targets classified as "potential lens candidates"...
We present measurements of the radial gravitational acceleration around isolated galaxies, comparing expected given baryonic matter with observed acceleration, using weak lensing from fourth data release Kilo-Degree Survey. These extend relation (RAR) by 2 decades into low-acceleration regime beyond outskirts observable galaxy. compare our RAR to predictions two modified gravity (MG) theories: MOND and Verlinde's emergent gravity. find that measured agrees well MG predictions. In addition,...
ABSTRACT We evaluate the consistency between lensing and clustering based on measurements from Baryon Oscillation Spectroscopic Survey combined with galaxy–galaxy Dark Energy (DES) Year 3, Hyper Suprime-Cam Subaru Strategic Program (HSC) 1, Kilo-Degree (KiDS)-1000. find good agreement these data sets. model observations using Emulator fit at two fixed cosmologies: Planck (S8 = 0.83), a Lensing cosmology 0.76). For joint analysis limited to large scales, we that both cosmologies provide an...
We conduct a pseudo- C ℓ analysis of the tomographic cross-correlation between 1000 deg 2 weak-lensing data from Kilo-Degree Survey (KiDS-1000) and thermal Sunyaev–Zeldovich (tSZ) effect measured by Planck Atacama Cosmology Telescope (ACT). Using HM X , halo-model-based approach that consistently models gas, star, dark matter components, we are able to derive constraints on both cosmology baryon feedback for first time these data, marginalising over redshift uncertainties, intrinsic...
We present a tomographic weak lensing analysis of the Kilo Degree Survey Data Release 4 (KiDS-1000), using new pseudo angular power spectrum estimator (pseudo- C ℓ ) under development for ESA Euclid mission. Over 21 million galaxies with shape information are divided into five redshift bins, ranging from 0.1 to 1.2 in photometric redshift. measured pseudo- eight bands multipole range 76 < 1500 auto- and cross-power spectra between bins. A series tests were carried out check systematic...
We present constraints on the flat $\Lambda$CDM cosmological model through a joint analysis of galaxy abundance, clustering and galaxy-galaxy lensing observables with Kilo-Degree Survey. Our theoretical combines flexible conditional stellar mass function, to describe galaxy-halo connection, N-body simulation-calibrated halo non-linear matter field. magnitude-limited bright sample 9-band optical-to-near-infrared photometry an extensive complete spectroscopic training provide accurate redshift...
We study projected underdensities in the cosmic galaxy density field known as 'troughs', and their overdense counterparts, which we call 'ridges'. identify these regions using a bright sample of foreground galaxies from photometric Kilo-Degree Survey (KiDS), specifically selected to mimic spectroscopic Galaxy And Mass Assembly survey (GAMA). Using background KiDS, measure weak gravitational lensing profiles troughs/ridges. quantify amplitude strength $A$ function percentile rank $P$...
We investigate possible signatures of halo assembly bias for spectroscopically selected galaxy groups from the Galaxy And Mass Assembly (GAMA) survey using weak lensing measurements spatially overlapping regions deeper, high-imaging-quality photometric Kilo-Degree Survey. use GAMA with an apparent richness larger than 4 to identify samples comparable mean host masses but a different radial distribution satellite galaxies, which is proxy formation time haloes. measure signal steeper average...
We measure the projected galaxy clustering and galaxy-galaxy lensing signals using Galaxy And Mass Assembly (GAMA) survey Kilo-Degree Survey (KiDS) to study bias. use concept of non-linear stochastic biasing in framework halo occupation statistics constrain parameters unveil origin biasing. The bias function $Γ_{\text{gm}}(r_{\text{p}})$, where $r_{\text{p}}$ is comoving separation, evaluated analytical model from which scale dependence non-linearity stochasticity models can be inferred. Our...
Abstract We present 97 new high-quality strong lensing candidates found in the final ∼350 deg 2 that complete full ∼1350 area of Kilo-Degree Survey (KiDS). Together with our previous findings, list from KiDS sums up to 268 systems. The sample is assembled using a convolutional neural network (CNN) classifier applied r -band (best-seeing) and g , i color-composited images separately. This optimizes complementarity morphology color information on identification candidates. apply classifiers...
We present a bright galaxy sample with accurate and precise photometric redshifts (photo-zs), selected using $ugriZYJHK_\mathrm{s}$ photometry from the Kilo-Degree Survey (KiDS) Data Release 4 (DR4). The highly pure complete dataset is flux-limited at $r<20$ mag, covers $\sim1000$ deg$^2$, contains about 1 million galaxies after artifact masking. exploit overlap Galaxy And Mass Assembly (GAMA) spectroscopy as calibration to determine photo-zs supervised machine learning neural network...
The physics of gravity on cosmological scales affects both the rate assembly large-scale structure, and gravitational lensing background light through this cosmic web. By comparing amplitude these different observational signatures, we can construct tests that distinguish general relativity from its potential modifications. We used latest weak dataset Kilo-Degree Survey, KiDS-1000, in conjunction with overlapping galaxy spectroscopic redshift surveys BOSS 2dFLenS, to perform most precise...
Galaxies and their dark matter haloes are part of a complex network mass structures, collectively called the cosmic web. Using tidal tensor prescription these structures can be classified into four environments: voids, sheets, filaments knots. As web may influence formation evolution galaxies they host, we aim to study effect environments on average galactic haloes. To this end measure galaxy–galaxy lensing profile 91 195 galaxies, within 0.039 < z 0.263, from spectroscopic Galaxy And Mass...
We present constraints on extensions to the standard cosmological model of a spatially flat Universe governed by general relativity, constant (Λ), and cold dark matter (CDM) varying spatial curvature Ω K , sum neutrino masses ∑ m ν energy equation state parameter w Hu-Sawicki f ( R ) gravity 0 parameter. With combined 3 × 2 pt measurements cosmic shear from Kilo-Degree Survey (KiDS-1000), galaxy clustering Baryon Oscillation Spectroscopic (BOSS), galaxy-galaxy lensing overlap between...
Photometric galaxy surveys, despite their limited resolution along the line of sight, encode rich information about large-scale structure (LSS) Universe thanks to high number density and extensive depth data. However, complicated selection effects in wide deep surveys can potentially cause significant bias angular two-point correlation function (2PCF) measured from those surveys. In this paper, we measure 2PCF newly published KiDS-Legacy sample. Given an r-band $5σ$ magnitude limit $24.8$...
We study the properties of luminous red galaxies (LRGs) selected from fourth data release Kilo Degree Survey (KiDS-1000) via galaxy-galaxy lensing background KiDS-1000. used a halo model formalism to interpret our measurements and obtain estimates masses as well satellite fractions LRGs, resulting in $2.7 h^ M ⊙ <M_ h $. studied strength intrinsic alignments (IA) using position-shape correlations function LRG luminosity, where we double power law describe relation between luminosity mass...