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The normalisation of the matter power spectrum, sigma_8, is an essential ingredient to predict the phenomenology of the low redshift universe. It has been measured using several methods, such as X-ray cluster counts, weak lensing and the…

Astrophysics · Physics 2008-11-26 A. Amara , A. Refregier

Late time cosmic acceleration may be achieved by modifying gravity on large scales. This should also have consequences on the evolution of perturbations. We thus extend our study of exponential infrared $f(T)$ teleparallel gravity to…

Cosmology and Nongalactic Astrophysics · Physics 2023-01-11 Mahmoud Hashim , Amr A. El-Zant , Waleed El Hanafy , Alexey Golovnev

Planned efforts to probe the largest observable distance scales in future cosmological surveys are motivated by a desire to detect relic correlations left over from inflation, and the possibility of constraining novel gravitational…

Cosmology and Nongalactic Astrophysics · Physics 2021-01-11 Caroline Guandalin , Julian Adamek , Philip Bull , Chris Clarkson , L. Raul Abramo , Louis Coates

Modern sky surveys are returning precision measurements of cosmological statistics such as weak lensing shear correlations, the distribution of galaxies, and cluster abundance. To fully exploit these observations, theorists must provide…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 Katrin Heitmann , Earl Lawrence , Juliana Kwan , Salman Habib , David Higdon

We measure the power spectrum of galaxy clustering in real space from the APM Galaxy Survey. We present an improved technique for the numerical inversion of Limber's equation that relates the angular clustering of galaxies to an integral…

Astrophysics · Physics 2009-11-07 N. D. Padilla , C. M. Baugh

We present a new numerical scheme to treat the non-linear evolution of cosmological power spectra. Governing equations for matter power spectra have been previously derived by a non-perturbative technique with closure approximation.…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-30 Takashi Hiramatsu , Atsushi Taruya

We find a simple, accurate model for the covariance matrix of the real-space cosmological matter power spectrum on slightly nonlinear scales (k~0.1-0.8 h/Mpc at z=0), where off-diagonal matrix elements become substantial. The model includes…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-30 Mark C. Neyrinck

I present a general discussion of the evolution and model-dependence of both the linear and nonlinear power spectrum of density fluctuations. The features of the linear power spectrum in cosmological models with cold dark matter (CDM) and…

Astrophysics · Physics 2009-10-31 Chung-Pei Ma

We reconstruct the non-linear matter power spectrum $P(k)$ using a joint analysis of gravitational lensing of the cosmic microwave background (CMB) and lensing of galaxies. This reconstruction is motivated by the $S_8$ tension between…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-11 Karen Perez Sarmiento , Alex Laguë , Mathew Madhavacheril , Bhuvnesh Jain , Blake Sherwin

We introduce two kurt-spectra to probe fourth-order statistics of weak lensing convergence maps. Using state-of-the-art numerical simulations, we study the shapes of these kurt-spectra as a function of source redshifts and smoothing angular…

Cosmology and Nongalactic Astrophysics · Physics 2022-11-16 Dipak Munshi , Hayden Lee , Cora Dvorkin , Jason D. McEwen

The upcoming stage IV wide-field surveys will provide high precision measurements of the large-scale structure (LSS) of the universe. Their interpretation requires fast and accurate theoretical predictions including large scales. For this…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-11 Laura Reymond , Alexander Reeves , Pierre Zhang , Alexandre Refregier

Cosmological information from forthcoming galaxy surveys, such as LSST and Euclid, will soon exceed that available from the CMB. Higher order correlation functions, like the bispectrum, will be indispensable for realising this potential.…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-06 Johnathan Hung , James R. Fergusson , E. P. S. Shellard

Defect reduction planning plays a vital role in enhancing software quality and minimizing software maintenance costs. By training a black box machine learning model and "explaining" its predictions, explainable AI for software engineering…

Software Engineering · Computer Science 2024-05-24 Khouloud Oueslati , Gabriel Laberge , Maxime Lamothe , Foutse Khomh

We propose a new approach, the calibrated nonparametric scan statistic (CNSS), for more accurate detection of anomalous patterns in large-scale, real-world graphs. Scan statistics identify connected subgraphs that are interesting or…

Methodology · Statistics 2022-06-28 Chunpai Wang , Daniel B. Neill , Feng Chen

The velocity divergence power spectrum is a key ingredient in modelling redshift space distortion effects on quasi-linear and nonlinear scales. We present an improved model for the z=0 velocity divergence auto and cross power spectrum which…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-24 Elise Jennings

Estimation of the angular power spectrum of the Cosmic Microwave Background (CMB) on a small patch of sky is usually plagued by serious spectral leakage, specially when the map has a hard edge. Even on a full sky map, point source masks can…

Astrophysics · Physics 2009-11-06 Sudeep Das , Amir Hajian , David N. Spergel

Photoacoustic computed tomography (PACT) is a promising imaging modality that combines the advantages of optical contrast with ultrasound detection. Utilizing ultrasound transducers with larger surface areas can improve detection…

The 3D matter power spectrum, $P_{\delta}(k,z)$ is a fundamental quantity in the analysis of cosmological data such as large-scale structure, 21cm observations, and weak lensing. Existing computer models (Boltzmann codes) such as CLASS can…

Cosmology and Nongalactic Astrophysics · Physics 2021-11-09 Arrykrishna Mootoovaloo , Andrew H. Jaffe , Alan F. Heavens , Florent Leclercq

We present a new power spectrum emulator named EuclidEmulator that estimates the nonlinear correction to the linear dark matter power spectrum. It is based on a spectral decomposition method called polynomial chaos expansion. All steps in…

One of the main science goals of the Large Synoptic Survey Telescope (LSST) is to uncover the nature of cosmic acceleration. In the base analysis, possible deviations from the Lambda-Cold-Dark-Matter ($\Lambda$CDM) background evolution will…

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