Henk Hoekstra
A5040514228- Galaxies: Formation, Evolution, Phenomena
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Cosmology and Gravitation Theories
- Gamma-ray bursts and supernovae
- Adaptive optics and wavefront sensing
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Advanced Vision and Imaging
- CCD and CMOS Imaging Sensors
- Remote Sensing in Agriculture
- Dark Matter and Cosmic Phenomena
- Calibration and Measurement Techniques
- History and Developments in Astronomy
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Particle physics theoretical and experimental studies
- Pulsars and Gravitational Waves Research
- Geophysics and Gravity Measurements
- Impact of Light on Environment and Health
- Black Holes and Theoretical Physics
Leiden University
2016-2025
Marconi University
2024
University College London
2012-2019
Leiden Observatory
2019
Mars Space (United Kingdom)
2018
European Space Astronomy Centre
2016
Queen's University
2014
Institut d'Astrophysique de Paris
2014
Astronomical Observatory of Rome
2014
University of Victoria
2005-2013
We present Advanced Camera for Surveys, NICMOS, and Keck adaptive-optics-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the Hubble Space Telescope (HST) Cluster Supernova Survey. The SNe were discovered over redshift interval 0.623 < z 1.415. Of these Ia, 14 pass our strict selection cuts are used in combination with world's sample to derive best current constraints on dark energy. new 10 beyond = 1, thereby nearly doubling statistical weight HST-discovered this redshift. Our...
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 $S_8=\sigma_8 \sqrt{\Omega_{\rm m}/0.3} =...
We present a finely-binned tomographic weak lensing analysis of the Canada-France-Hawaii Telescope Lensing Survey, CFHTLenS, mitigating contamination to signal from presence intrinsic galaxy alignments via simultaneous fit cosmological model and an alignment model. CFHTLenS spans 154 square degrees in five optical bands, with accurate shear photometric redshifts for sample median redshift zm =0.70. estimate 21 sets cosmic correlation functions associated six bins, each spanning angular range...
We present a catalog of galaxy clusters selected via their Sunyaev-Zel'dovich (SZ) effect signature from 2500 deg$^2$ South Pole Telescope (SPT) data. This work represents the complete sample detected at high significance in 2500-square-degree SPT-SZ survey, which was completed 2011. A total 677 (409) cluster candidates are identified above signal-to-noise threshold $\xi$ =4.5 (5.0). Ground- and space-based optical near-infrared (NIR) imaging confirms overdensities similarly colored galaxies...
We present the Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS) that accurately determines a weak gravitational lensing signal from full 154 square degrees of deep multi-colour data obtained by CFHT Legacy Survey. Weak large-scale structure is widely recognised as one most powerful but technically challenging probes cosmology. outline CFHTLenS analysis pipeline, describing how and why every step chain raw pixel to shear photometric redshift measurement has been revised improved...
The Shear TEsting Programme, STEP, is a collaborative project to improve the accuracy and reliability of all weak lensing measurements in preparation for next generation wide-field surveys. In this first STEP paper we present results blind analysis simulated ground-based observations relatively simple galaxy morphologies. most successful methods are shown achieve percent level accuracy. From cosmic shear pipelines that have been used constrain cosmology, find measured an within statistical...
ABSTRACT The Next Generation Virgo Cluster Survey (NGVS) is a program that uses the 1 deg 2 MegaCam instrument on Canada–France–Hawaii Telescope to carry out comprehensive optical imaging survey of cluster, from its core virial radius—covering total area 104 —in u * griz bandpasses. Thanks dedicated data acquisition strategy and processing pipeline, NGVS reaches point-source depth g ≈ 25.9 mag (10σ) surface brightness limit μ ∼ 29 arcsec −2 (2σ above mean sky level), thus superseding all...
A likelihood-based method for measuring weak gravitational lensing shear in deep galaxy surveys is described and applied to the Canada–France–Hawaii Telescope (CFHT) Lensing Survey (CFHTLenS). CFHTLenS comprises 154 deg2 of multi-colour optical data from CFHT Legacy Survey, with measurements being made i′ band a depth i′AB < 24.7, galaxies signal-to-noise ratio νSN ≳ 10. The based on lensfit algorithm earlier papers, but here we describe full analysis pipeline that takes into account...
We present data products from the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS). CFHTLenS is based on Wide component of Legacy (CFHTLS). It encompasses 154 deg2 deep, optical, high-quality, sub-arcsecond imaging in five optical filters u*g′r′i′z′. The scientific aims team are weak gravitational lensing studies supported by photometric redshift estimates for galaxies. This paper presents our processing complete set. were able to obtain a set with very good image quality and...
Weak gravitational lensing is a unique probe of the dark side universe: it provides direct way to map distribution matter around galaxies, clusters galaxies and on cosmological scales. Furthermore, measurement induced distortions shapes distant powerful energy. In this review we describe how measurements are made interpreted. We discuss various systematic effects that can hamper progress they may be overcome. some recent results in weak by galaxy cosmic shear prospects for energy from...
Masses of clusters galaxies from weak gravitational lensing analyses ever larger samples are increasingly used as the reference to which baryonic scaling relations compared.In this paper we revisit analysis a sample 50 studied part Canadian Cluster Comparison Project.We examine key sources systematic error in cluster masses.We quantify robustness our shape measurements and calibrate algorithm empirically using extensive image simulations.The source redshift distribution is revised latest...
The Kilo-Degree Survey (KiDS) is a multi-band imaging survey designed for cosmological studies from weak lensing and photometric redshifts. It uses the European Southern Observatory VLT Telescope with its wide-field camera OmegaCAM. KiDS images are taken in four filters similar to Sloan Digital Sky ugri bands. best seeing time reserved deep r-band observations. median 5σ limiting AB magnitude 24.9 below 0.7 arcsec. Initial observations have concentrated on Galaxy Mass Assembly (GAMA) regions...
We present an exploration of weak lensing by large-scale structure in the linear regime, using third-year (T0003) CFHTLS Wide data release. Our results place tight constraints on scaling amplitude matter power spectrum sigma_8 with density Omega_m. Spanning 57 square degrees to i'_AB = 24.5 over three independent fields, unprecedented contiguous area this survey permits high signal-to-noise measurements two-point shear statistics from 1 arcmin 4 degrees. Understanding systematic errors our...
We present cosmological constraints from 2D weak gravitational lensing by the large-scale structure in Canada-France Hawaii Telescope Lensing Survey (CFHTLenS) which spans 154 square degrees five optical bands. Using accurate photometric redshifts and measured shapes for 4.2 million galaxies between of 0.2 1.3, we compute cosmic shear correlation function over angular scales ranging 0.8 350 arcmin. non-linear models dark-matter power spectrum, constrain parameters exploring parameter space...
We present a tomographic cosmological weak lensing analysis of the HST COSMOS Survey. Applying our lensing-optimized data reduction, principal component interpolation for ACS PSF, and improved modelling charge-transfer inefficiency, we measure signal which is consistent with pure gravitational modes no significant shape systematics. carefully estimate statistical uncertainty from simulated COSMOS-like fields obtained ray-tracing through Millennium Simulation. test pipeline on space-based...
The Euclid space telescope will measure the shapes and redshifts of galaxies to reconstruct expansion history Universe growth cosmic structures. Estimation expected performance experiment, in terms predicted constraints on cosmological parameters, has so far relied different methodologies numerical implementations, developed for observational probes their combination. In this paper we present validated forecasts, that combine both theoretical expertise probes. This is presented provide...
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...
The Kilo-Degree Survey (KiDS) is an optical wide-field imaging survey carried out with the VLT Telescope and OmegaCAM camera. KiDS will image 1500 square degrees in four filters (ugri), together its near-infrared counterpart VIKING produce deep photometry nine bands. Designed for weak lensing shape photometric redshift measurements, core science driver of mapping large-scale matter distribution Universe back to a ~0.5. Secondary cases are manifold, covering topics such as galaxy evolution,...
We perform a combined analysis of cosmic shear tomography, galaxy-galaxy lensing and redshift-space multipole power spectra (monopole quadrupole) using 450 deg$^2$ imaging data by the Kilo Degree Survey (KiDS) overlapping with two spectroscopic surveys: 2-degree Field Lensing (2dFLenS) Baryon Oscillation Spectroscopic (BOSS). restrict spectrum measurements to regions KiDS, self-consistently compute full covariance between different observables large suite $N$-body simulations. methodically...
Galaxy masses play a fundamental role in our understanding of structure formation models. This review addresses the variety and reliability mass estimators that pertain to stars, gas, dark matter. The different sections on from stellar populations, dynamical gas-rich gas-poor galaxies, with some attention paid Milky Way, weak strong lensing methods all provide material galaxy self-consistent manner.