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Deep metric learning aims to learn an embedding space, where semantically similar samples are close together and dissimilar ones are repelled against. To explore more hard and informative training signals for augmentation and…

计算机视觉与模式识别 · 计算机科学 2022-11-30 Zheren Fu , Zhendong Mao , Bo Hu , An-An Liu , Yongdong Zhang

The B-(curl-)mode of the correlation of galaxy ellipticities (shear) can be used to detect a stochastic gravitational wave background, such as that predicted by inflation. In this paper, we derive the tensor mode contributions to shear from…

宇宙学与河外天体物理 · 物理学 2013-11-27 Fabian Schmidt , Donghui Jeong

We identify and study a previously unknown systematic effect on cosmic shear measurements, caused by the selection of galaxies used for shape measurement, in particular the rejection of close (blended) galaxy pairs. We use ray-tracing…

宇宙学与河外天体物理 · 物理学 2015-05-20 Jan Hartlap , Stefan Hilbert , Peter Schneider , Hendrik Hildebrandt

We introduce a self-calibration method that can be applied to the intrinsic ellipticity--intrinsic ellipticity (II) and gravitational shear -- intrinsic ellipticity (GI) types of intrinsic alignment of galaxies. The method combines previous…

宇宙学与河外天体物理 · 物理学 2018-12-05 Ji Yao , Mustapha Ishak , M. A. Troxel

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…

The ratio of the average tangential shear signal of different weak lensing source populations around the same lens galaxies, also known as a shear ratio, provides an important test of lensing systematics and a potential source of…

宇宙学与河外天体物理 · 物理学 2024-11-01 Ni Emas , Chris Blake , Rossana Ruggeri , Anna Porredon

We measure the weak lensing shear around galaxy troughs, i.e. the radial alignment of background galaxies relative to underdensities in projections of the foreground galaxy field over a wide range of redshift in Science Verification data…

The weak gravitational lensing of distant galaxies by large-scale structure is expected to become a powerful probe of dark energy. By measuring the ellipticities of large numbers of background galaxies, the subtle gravitational distortion…

天体物理学 · 物理学 2014-11-18 Charles Shapiro

Cosmic shear is a powerful probe of cosmological parameters, but its potential can be fully utilised only if galaxy shapes are measured with great accuracy. Two major effects have been identified which are likely to account for most of the…

宇宙学与河外天体物理 · 物理学 2017-03-08 Tomasz Kacprzak , Sarah Bridle , Barnaby Rowe , Lisa Voigt , Joe Zuntz , Michael Hirsch , Niall MacCrann

Current and upcoming imaging galaxy surveys are pushing galaxy samples to higher and higher redshifts. This push will be more pronounced for lens galaxies, for which we only need to measure galaxy positions, not shapes. As a result, we will…

宇宙学与河外天体物理 · 物理学 2024-10-02 Dane N. Cross , Carles Sánchez

Using data from the Pantheon SN Ia compilation and the Sloan Digital Sky Survey (SDSS), we propose an estimator for weak lensing convergence incorporating positional and photometric data of foreground galaxies. The correlation between this…

宇宙学与河外天体物理 · 物理学 2022-07-06 Paul Shah , Pablo Lemos , Ofer Lahav

We study the impact of modified gravity of the Horndeski class, on intrinsic shape correlations in cosmic shear surveys. As intrinsic shape correlations (IAs) are caused by tidal gravitational fields acting on galaxies as a collection of…

宇宙学与河外天体物理 · 物理学 2022-01-26 Robert Reischke , Victor Bosca , Tim Tugendhat , Björn Malte Schäfer

We report a detection of the coherent distortion of faint galaxies arising from gravitational lensing by foreground structures. This ``cosmic shear'' is potentially the most direct measure of the mass power spectrum, as it is unaffected by…

天体物理学 · 物理学 2011-05-05 David Bacon , Alexandre Refregier , Richard Ellis

We present DELTA (Data-Empiric Learned Tidal Alignments), a deep learning model that isolates galaxy intrinsic alignments (IAs) from weak lensing distortions using only observational data. The model uses an Equivariant Graph Neural Network…

宇宙学与河外天体物理 · 物理学 2025-06-11 Matthew Craigie , Eric Huff , Yuan-Sen Ting , Rossana Ruggeri , Tamara M. Davis

The galaxy intrinsic alignment is a severe challenge to precision cosmic shear measurement. We propose to self-calibrate the induced gravitational shear-galaxy intrinsic ellipticity correlation (the GI correlation, \citealt{Hirata04b}) in…

天体物理学 · 物理学 2011-04-07 Pengjie Zhang

We present an assessment of the accuracy of common operations performed in $21$-cm spectral line stacking experiments. To this end, we generate mock interferometric data surveying the 21-cm emission at frequency $1310<\nu<1420$ MHz…

宇宙学与河外天体物理 · 物理学 2022-06-22 Francesco Sinigaglia , Ed Elson , Giulia Rodighiero , Mattia Vaccari

One of the primary limiting sources of systematic uncertainty in forthcoming weak lensing measurements is systematic uncertainty in the quantitative relationship between the distortions due to gravitational lensing and the measurable…

宇宙学与河外天体物理 · 物理学 2017-02-10 Eric Huff , Rachel Mandelbaum

We propose a novel method to detect cosmic magnification signals by cross-correlating foreground convergence fields constructed from galaxy shear measurements with background galaxy positional distributions, namely shear-number density…

宇宙学与河外天体物理 · 物理学 2021-06-07 Xiangkun Liu , Dezi Liu , Zucheng Gao , Chengliang Wei , Guoliang Li , Liping Fu , Toshifumi Futamase , Zuhui Fan

Using a sample of 608 Type Ia supernovae from the SDSS-II and BOSS surveys, combined with a sample of foreground galaxies from SDSS-II, we estimate the weak lensing convergence for each supernova line-of-sight. We find that the correlation…

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