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We present a variational-Bayes solution to compute non-Gaussian posteriors from extremely expensive likelihoods. Our approach is an alternative for parameter inference when MCMC sampling is numerically prohibitive or conceptually…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-13 Matteo Rizzato , Elena Sellentin

Likelihood-free inference provides a rigorous approach to preform Bayesian analysis using forward simulations only. The main advantage of likelihood-free methods is its ability to account for complex physical processes and observational…

Cosmology and Nongalactic Astrophysics · Physics 2022-02-09 Sut-Ieng Tam , Keiichi Umetsu , Adam Amara

An accurate covariance matrix is essential for obtaining reliable cosmological results when using a Gaussian likelihood. In this paper we study the covariance of pseudo-$C_\ell$ estimates of tomographic cosmic shear power spectra. Using two…

We introduce the skew-spectrum statistic for weak lensing convergence $\kappa$ maps and test it against state-of-the-art high-resolution all-sky numerical simulations. We perform the analysis as a function of source redshift and smoothing…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-14 D. Munshi , T. Namikawa , T. D. Kitching , J. D. McEwen , F. R. Bouchet

Weak lensing mass-mapping is a useful tool to access the full distribution of dark matter on the sky, but because of intrinsic galaxy ellipticies and finite fields/missing data, the recovery of dark matter maps constitutes a challenging…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-05 Benjamin Remy , Francois Lanusse , Niall Jeffrey , Jia Liu , Jean-Luc Starck , Ken Osato , Tim Schrabback

Weak lensing experiments are a powerful probe of cosmology through their measurement of the mass distribution of the universe. A challenge for this technique is to control systematic errors that occur when measuring the shapes of distant…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-04 Alexandre Refregier , Tomasz Kacprzak , Adam Amara , Sarah Bridle , Barnaby Rowe

Weak lensing will play an important role in future cosmological surveys, including e.g. Euclid and SKA. Sufficiently accurate theoretical predictions are important for correctly interpreting these surveys and hence for extracting correct…

Cosmology and Nongalactic Astrophysics · Physics 2019-05-07 Sofie Marie Koksbang , Chris Clarkson

Transfer-matrix methods are used to study the probability distributions of spin-spin correlation functions $G$ in the two-dimensional random-field Ising model, on long strips of width $L = 3 - 15$ sites, for binary field distributions at…

Statistical Mechanics · Physics 2009-10-31 S. L. A. de Queiroz , R. B. Stinchcombe

Assuming a Euclid-like weak lensing data set, we compare different methods of dealing with its inherent parameter degeneracies. Including priors into a data analysis can mask the information content of a given data set alone. However, since…

Cosmology and Nongalactic Astrophysics · Physics 2016-01-27 Elena Sellentin , Björn Malte Schäfer

Recent studies have demonstrated that {\em secondary} non-Gaussianity induced by gravity will be detected with a high signal-to-noise (S/N) by future and even by on-going weak lensing surveys. One way to characterise such non-Gaussianity is…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-05 D. Munshi , T. Namikawa , T. D. Kitching , J. D. McEwen , R. Takahashi , F. R. Bouchet , A. Taruya , B. Bose

The statistics of gravitational lensing can provide us with a very powerful probe of the mass distribution of matter in the universe. By comparing predicted strong lensing probabilities with observations, we can test the mass distribution…

Astrophysics · Physics 2009-11-10 Tong-Jie Zhang

Observational evidence shows that gravitational lensing induces an angular correlation between the distribution of galaxies and much more distant QSOs. We use weak gravitational lensing theory to calculate this angular correlation, updating…

We present a joint weak lensing and X-ray analysis of 4 deg$^2$ from the CFHTLS and XMM-LSS surveys. Our weak lensing analysis is the first analysis of a real survey using shapelets, a new generation weak lensing analysis method. We create…

We compute statistical properties of weak gravitational lensing by large-scale structure in three Cold Dark Matter models. We use a P$^3$M $N$-body code to simulate the formation and evolution of large-scale structure in the universe. We…

Astrophysics · Physics 2009-10-31 Takashi Hamana , Hugo Martel , Toshifumi Futamase

We describe an efficient algorithm for calculating the statistics of weak lensing by large-scale structure based on a tiled set of independent particle-mesh N-body simulations which telescope in resolution along the line of sight. This…

Astrophysics · Physics 2008-11-26 Martin White , Wayne Hu

Weak gravitational lensing requires precise measurements of galaxy shapes and therefore an accurate knowledge of the PSF model. The latter can be a source of systematics that affect the shear two-point correlation function. A key stake of…

The one-point probability distribution function (PDF) is a powerful summary statistic for non-Gaussian cosmological fields, such as the weak lensing (WL) convergence reconstructed from galaxy shapes or cosmic microwave background (CMB)…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-04 Leander Thiele , J. Colin Hill , Kendrick M. Smith

We describe a weak lensing view of the downsizing of star forming galaxies based on cross correlating a weak lensing ($\kappa$) map with a predicted map constructed from a redshift survey. Moderately deep and high resolution images with…

The next generation of weak gravitational lensing surveys has the potential to place stringent constraints on cosmological parameters. However, their analysis is limited by systematics such as the intrinsic alignments of galaxies, which…

Cosmology and Nongalactic Astrophysics · Physics 2025-04-18 Max E. Lee , Zoltán Haiman , Shivam Pandey , Shy Genel

We study how well the Gaussian approximation is valid for computing the covariance matrices of the convergence power and bispectrum in weak gravitational lensing analyses. We focus on its impact on the cosmological parameter estimations by…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Masanori Sato , Takahiro Nishimichi