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Weak lensing by large-scale structure is a powerful probe of cosmology if the apparent alignments in the shapes of distant galaxies can be accurately measured. Most studies have therefore focused on improving the fidelity of the shape…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-24 Henk Hoekstra , Arun Kannawadi , Thomas D. Kitching

The first half of this paper explores the origin of systematic biases in the measurement of weak gravitational lensing. Compared to previous work, we expand the investigation of PSF instability and fold in for the first time the effects of…

SURFSUP is a joint Spitzer and HST Exploration Science program using 10 galaxy clusters as cosmic telescopes to study z >~ 7 galaxies at intrinsically lower luminosities, enabled by gravitational lensing, than blank field surveys of the…

We present our cosmic shear analysis of GEMS, one of the largest wide-field surveys ever undertaken by the Hubble Space Telescope. Imaged with the Advanced Camera for Surveys (ACS), GEMS spans 795 square arcmin in the Chandra Deep Field…

The Transiting Exoplanet Survey Satellite (TESS) will observe $\sim$150~million stars brighter than $T_{\rm mag} \approx 16$, with photometric precision from 60~ppm to 3~percent, enabling an array of exoplanet and stellar astrophysics…

Instrumentation and Methods for Astrophysics · Physics 2018-09-05 Ryan J. Oelkers , Keivan G. Stassun

We apply a mass reconstruction technique to simulated large-scale structure gravitational distortion maps, from 2.5' to 10 degree scales, for different cosmological scenarii. The projected mass is reconstructed using a non-parametric least…

Astrophysics · Physics 2007-05-23 L. Van Waerbeke , F. Bernardeau , Y. Mellier

We present the methodology for a joint cosmological analysis of weak gravitational lensing from the fourth data release of the ESO Kilo-Degree Survey (KiDS-1000) and galaxy clustering from the partially overlapping BOSS and 2dFLenS surveys.…

Observationally, weak lensing has been served so far by optical surveys due to the much larger number densities of background galaxies achieved, which is typically by two to three orders of magnitude compared to radio. However, the high…

Instrumentation and Methods for Astrophysics · Physics 2016-03-18 Marzia Rivi , Lance Miller , Sphesihle Makhathini , Filipe Batoni Abdalla

We present the weak lensing methodology applied to our multi-colour imaging survey of X-ray luminous galaxy clusters conducted with the wide field CFH12k camera. This method, which is converting a fully reduced CFH12k image into cluster…

Astrophysics · Physics 2009-11-10 S. Bardeau , J. -P. Kneib , O. Czoske , G. Soucail , I. Smail , H. Ebeling , G. P. Smith

We present weak-lensing mass measurements of 50 X-ray luminous galaxy clusters at $0.15\le z\le0.3$, based on uniform high quality observations with Suprime-Cam mounted on the 8.2-m Subaru telescope. We pay close attention to possible…

Cosmology and Nongalactic Astrophysics · Physics 2016-08-03 Nobuhiro Okabe , Graham P. Smith

Weak gravitational lensing observations are a key science driver for the NASA Wide Field Infrared Survey Telescope (WFIRST). To validate the performance of the WFIRST infrared detectors, we have performed a laboratory emulation of weak…

Instrumentation and Methods for Astrophysics · Physics 2015-06-16 Suresh Seshadri , Charles Shapiro , Timothy Goodsall , Jason Fucik , Christopher M. Hirata , Jason Rhodes , Barnaby Rowe , Roger Smith

We present and describe im3shape, a new publicly available galaxy shape measurement code for weak gravitational lensing shear. im3shape performs a maximum likelihood fit of a bulge-plus-disc galaxy model to noisy images, incorporating an…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Joe Zuntz , Tomasz Kacprzak , Lisa Voigt , Michael Hirsch , Barnaby Rowe , Sarah Bridle

We present a simulation analysis of weak gravitational lensing flexion and shear measurement using shapelet decomposition, and identify differences between flexion and shear measurement noise in deep survey data. Taking models of galaxies…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Barnaby Rowe , David Bacon , Richard Massey , Catherine Heymans , Boris Haeussler , Andy Taylor , Jason Rhodes , Yannick Mellier

We present our results from training and evaluating a convolutional neural network (CNN) to predict galaxy shapes from wide-field survey images of the first data release of the Dark Energy Survey (DES DR1). We use conventional shape…

Cosmology and Nongalactic Astrophysics · Physics 2019-09-25 Dezső Ribli , László Dobos , István Csabai

Weak gravitational lensing has the potential to place tight constraints on the equation of the state of dark energy. However, this will only be possible if shear measurement methods can reach the required level of accuracy. We present a new…

Instrumentation and Methods for Astrophysics · Physics 2015-05-13 Guldariya Nurbaeva , Malte Tewes , Frederic Courbin , Georges Meylan

Weak gravitational lensing is one of the key probes of cosmology. Cosmic shear surveys aimed at measuring the distribution of matter in the universe are currently being carried out (Pan-STARRS) or planned for the coming decade (DES, LSST,…

Cosmology and Nongalactic Astrophysics · Physics 2013-11-22 Alberto Vallinotto

We measure seeing-corrected ellipticities for 2 x 10^6 galaxies with magnitude R<23 in 12 widely separated fields totalling 75 deg^2 of sky. At angular scales >30\arcmin, ellipticity correlations are detected at high significance and…

Astrophysics · Physics 2015-06-24 M. Jarvis , G. Bernstein , B. Jain , P. Fischer , D. Smith , J. A. Tyson , D. Wittman

Weak gravitational lensing analyses are fundamentally limited by the intrinsic, non-Gaussian distribution of galaxy shapes. We explore alternative statistics for samples of ellipticity measurements that are unbiased, efficient, and robust.…

Cosmology and Nongalactic Astrophysics · Physics 2018-01-31 Merijn Smit , Konrad Kuijken

Gravitational lensing shear has the potential to be the most powerful tool for constraining the nature of dark energy. However, accurate measurement of galaxy shear is crucial and has been shown to be non-trivial by the Shear TEsting…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 L. M. Voigt , S. L. Bridle

We explore the cosmological constraints from cosmic shear using a new way of modelling the non-linear matter correlation functions. The new formalism extends the method of Angulo & White (2010), which manipulates outputs of $N$-body…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-19 Raul E. Angulo , Stefan Hilbert