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Related papers: Transients from Zel'dovich initial conditions

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Conventional approaches for simulating steady-state distributions of particles under diffusive and advective transport at high P\'eclet numbers involve solving the diffusion and advection equations in at least two dimensions. Here, we…

We use a hydrodynamical N-body code to generate simulated maps, of size one square degree, of the thermal SZ effect. We study three different cosmologies; the currently-favoured low-density model with a cosmological constant, a…

Astrophysics · Physics 2016-08-30 Antonio C da Silva , Domingos Barbosa , Andrew R Liddle , Peter A Thomas

The accurate estimation of photometric redshifts is crucial to many upcoming galaxy surveys, for example the Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST). Almost all Rubin extragalactic and cosmological science requires…

Instrumentation and Methods for Astrophysics · Physics 2022-05-04 Natalia Stylianou , Alex I. Malz , Peter Hatfield , John Franklin Crenshaw , Julia Gschwend

Many spatial models exhibit locality structures that effectively reduce their intrinsic dimensionality, enabling efficient approximation and sampling of high-dimensional distributions. However, existing approximation techniques primarily…

Machine Learning · Statistics 2026-02-02 Tiangang Cui , Shuigen Liu , Xin T. Tong

We apply Bayesian statistics with prior probabilities of galaxy surface luminosity (SL) to improve photometric redshifts. We apply the method to a sample of 1266 galaxies with spectroscopic redshifts in the GOODS North and South fields at…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 Lifang Xia , Seth Cohen , Sangeeta Malhotra , James Rhoads , Norman Grogin , Nimish P. Hathi , Rogier A. Windhorst , Nor Pirzkal , Chun Xu

In this work, we revisit the scaling analysis and commonly accepted conditions for the validity of the standard, reverse and total quasi-steady-state approximations through the lens of dimensional Tikhonov-Fenichel parameters and their…

Dynamical Systems · Mathematics 2023-03-21 Justin Eilertsen , Santiago Schnell

The Sunyaev-Zel'dovich (SZ) effect is a powerful tool for studying clusters of galaxies and cosmology. Large mm-wave telescopes are now routinely detecting and mapping the SZ effect in a number of clusters, measure their comptonisation…

Cosmology and Nongalactic Astrophysics · Physics 2012-04-09 Paolo de Bernardis , Sergio Colafrancesco , Giuseppe D' Alessandro , Luca Lamagna , Paolo Marchegiani , Silvia Masi , Alessandro Schillaci

According to modern developments in turbulence theory, the "dissipation" scales (u.v. cut-offs) $\eta$ form a random field related to velocity increments $\delta_{\eta}u$. In this work we, using Mellin's transform combined with the Gaussain…

Fluid Dynamics · Physics 2009-11-11 Victor Yakhot

We survey our recent articles dealing with one dimensional attractive zero range processes moving under site disorder. We suppose that the underlying random walks are biased to the right and so hyperbolic scaling is expected. Under the…

Probability · Mathematics 2020-08-17 Christophe Bahadoran , Thomas Mountford , K. Ravishankar , Ellen Saada

We examine how coupled dark matter and dark energy modify the development of Zel'dovich pancakes. We study how the various effects of these theories, such as a fifth force in the dark sector and a modified particle Hubble drag, produce…

Astrophysics · Physics 2008-02-14 P. M. Sutter , P. M. Ricker

We run very large cosmological N-body hydrodynamical simulations in order to study statistically the baryon fractions in early dark matter halos. We critically examine how differences in the initial conditions affect the gas fraction in the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Smadar Naoz , Naoki Yoshida , Rennan Barkana

The low-T part of the phase diagram in self-assembling systems is correctly predicted by the known versions of the density functional theory (DFT). The high-T part obtained in DFT, however, does not agree with simulations even on the…

Soft Condensed Matter · Physics 2018-11-20 A. Ciach

In this work, we derive particle schemes, based on micro-macro decomposition, for linear kinetic equations in the diffusion limit. Due to the particle approximation of the micro part, a splitting between the transport and the collision part…

Numerical Analysis · Mathematics 2017-01-19 Anaïs Crestetto , Nicolas Crouseilles , Mohammed Lemou

We present a new training set for estimating empirical photometric redshifts of galaxies, which was created as part of the 2dFLenS project. This training set is located in a 700 sq deg area of the KiDS South field and is randomly selected…

The scientific impact of current and upcoming photometric galaxy surveys is contingent on our ability to obtain redshift estimates for large numbers of faint galaxies. In the absence of spectroscopically confirmed redshifts, broad-band…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-14 Alex I. Malz

We obtain two theorems extending the use of a saddlepoint approximation to multiparameter problems for likelihood ratio-like statistics which allow their use in permutation and rank tests and could be used in bootstrap approximations. In…

Statistics Theory · Mathematics 2012-03-15 John Kolassa , John Robinson

Accurate modeling of nonlinearities in the galaxy bispectrum, the Fourier transform of the galaxy three-point correlation function, is essential to fully exploit it as a cosmological probe. In this paper, we present numerical and…

Cosmology and Nongalactic Astrophysics · Physics 2015-12-02 Nuala McCullagh , Donghui Jeong , Alexander S. Szalay

Despite the high accuracy of photometric redshifts (zphot) derived using Machine Learning (ML) methods, the quantification of errors through reliable and accurate Probability Density Functions (PDFs) is still an open problem. First, because…

We describe a new method for measuring the true redshift distribution of any set of objects studied only photometrically. The angular cross-correlation between objects in a photometric sample with objects in some spectroscopic sample as a…

Astrophysics · Physics 2009-11-13 Jeffrey A. Newman

This paper aims to put constraints on the transition redshift $z_t$, which determines the onset of cosmic acceleration, in cosmological-model independent frameworks. In order to do that, we use the non-parametric Gaussian Process method…

Cosmology and Nongalactic Astrophysics · Physics 2020-05-20 J. F. Jesus , R. Valentim , A. A. Escobal , S. H. Pereira
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