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Throughout cosmological simulations, the properties of the matter density field in the initial conditions have a decisive impact on the features of the structures formed today. In this paper we use a random-forest classification algorithm…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-20 Jazhiel Chacón , J. Alberto Vázquez , Erick Almaraz

The late-time nonlinear Lagrangian displacement field is highly correlated with the initial field, so reconstructing it could enable us to extract primordial cosmological information. Our previous work [1] carefully studied the displacement…

Cosmology and Nongalactic Astrophysics · Physics 2024-01-25 Atsuhisa Ota , Hee-Jong Seo , Shun Saito , Florian Beutler

One way of recovering information about the initial conditions of the Universe is by measuring features of the cosmological density field which are preserved during gravitational evolution and galaxy formation. In this paper we study the…

Astrophysics · Physics 2016-08-30 Rupert A. C. Croft , Enrique Gaztanaga

We revise the Bayesian inference steps required to analyse the cosmological large-scale structure. Here we make special emphasis in the complications which arise due to the non-Gaussian character of the galaxy and matter distribution. In…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-03 Francisco-Shu Kitaura

From the nature of dark matter to the rate of expansion of our Universe, observations of distant galaxies distorted through strong gravitational lensing have the potential to answer some of the major open questions in astrophysics. Modeling…

Cosmology and Nongalactic Astrophysics · Physics 2022-10-18 Siddharth Mishra-Sharma , Ge Yang

Amongst the most popular explanations for dark energy are modified theories of gravity. The galaxy overdensity and peculiar velocity fields help us to constrain the growth rate of structure and distinguish different models of gravity. We…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-20 Yan Lai , Cullan Howlett , Tamara M. Davis

We present an alternative, Bayesian method for large-scale reconstruction from observed peculiar velocity data. The method stresses a rigorous treatment of the random errors and it allows extrapolation into poorly sampled regions in real…

Astrophysics · Physics 2009-10-31 Saleem Zaroubi , Yehuda Hoffman , Avishai Dekel

We present the first results from the Manticore project, dubbed Manticore-Local, a suite of Bayesian constrained simulations of the nearby Universe, generated by fitting a physical structure formation model to the 2M++ galaxy catalogue…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-19 Stuart McAlpine , Jens Jasche , Metin Ata , Guilhem Lavaux , Richard Stiskalek , Carlos S. Frenk , Adrian Jenkins

High-fidelity reconstruction of fluids from sparse multiview RGB videos remains a formidable challenge due to the complexity of the underlying physics as well as complex occlusion and lighting in captures. Existing solutions either assume…

Reconstructing the initial conditions of the Universe from late-time observations has the potential to optimally extract cosmological information. Due to the high dimensionality of the parameter space, a differentiable forward model is…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-19 Adrian E. Bayer , Chirag Modi , Simone Ferraro

Analyses of peculiar velocity surveys face several challenges, including low signal--to--noise in individual velocity measurements and the presence of small--scale, nonlinear flows. This is the second in a series of papers in which we…

Astrophysics · Physics 2009-11-07 Hume A. Feldman , Richard Watkins , Adrian L. Melott , Scott W. Chambers

Reconstructing the Gaussian initial conditions at the beginning of the Universe from the survey data in a forward modeling framework is a major challenge in cosmology. This requires solving a high dimensional inverse problem with an…

Cosmology and Nongalactic Astrophysics · Physics 2021-04-28 Chirag Modi , François Lanusse , Uroš Seljak , David N. Spergel , Laurence Perreault-Levasseur

The peculiar velocity reconstruction methods allow one to have a deeper insight into the distribution of dark matter: both to measure mean matter density and to obtain the primordial density fluctuations. We present here the…

Astrophysics · Physics 2015-05-13 G. Lavaux , R. Mohayaee , S. Colombi , R. B. Tully

We discuss the implementation of Bayesian inversion methods in order to recover the properties of the intergalactic medium from observations of the neutral hydrogen Lyman-$\alpha$ absorptions observed in the spectra of high redshift quasars…

Astrophysics · Physics 2009-11-06 C. Pichon , J. L. Vergely , E. Rollinde , S. Colombi , P. Petitjean

We present a method to reconstruct the initial conditions of the universe using observed galaxy positions and luminosities under the assumption that the luminosities can be calibrated with weak lensing to give the mean halo mass. Our method…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-24 Chirag Modi , Yu Feng , Uros Seljak

The evolved cosmological matter density field is fully determined by the initial matter density field at fixed cosmological parameters. However, the two-dimensional cosmological projected matter density field, relevant for weak-lensing and…

Cosmology and Nongalactic Astrophysics · Physics 2025-10-17 Kevin Hong , Rugved Pund , Anže Slosar

A new fast Bayesian approach is introduced for the detection of discrete objects immersed in a diffuse background. This new method, called PowellSnakes, speeds up traditional Bayesian techniques by: i) replacing the standard form of the…

Astrophysics · Physics 2009-11-13 Pedro Carvalho , Graca Rocha , M. P. Hobson

We propose a new method to recover the cosmological initial conditions of the presently observed galaxy distribution, which can serve to run constrained simulations of the Local Universe. Our method, the Reverse Zeldovich Approximation…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Timur Doumler , Yehuda Hoffman , Helene Courtois , Stefan Gottloeber

We present a numerical study of the cosmic density vs. velocity divergence relation (DVDR) in the mildly non-linear regime. We approximate the dark matter as a non-relativistic pressureless fluid, and solve its equations of motion on a grid…

Astrophysics · Physics 2009-10-31 Andrzej Kudlicki , Michal Chodorowski , Tomasz Plewa , Michal Różyczka

Naturalness problems such as the hierarchy problem and the origin of dark energy remain significant challenges in modern cosmology. This paper develops a rigorous mathematical framework where each observer defines their own universe, and…

General Relativity and Quantum Cosmology · Physics 2025-05-13 Ruby P. Madeimy
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