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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 explore the possibility of retrieving cosmological information from 21-cm tomographic data at intermediate redshift. The first step in our approach consists of training an encoder, composed of several three dimensional convolutional…

Instrumentation and Methods for Astrophysics · Physics 2025-07-30 Sambatra Andrianomena

We study the use of U-Nets in reconstructing the linear dark matter density field and its consequences for constraining cosmological parameters, in particular primordial non-Gaussianity. Our network is able to reconstruct the initial…

Cosmology and Nongalactic Astrophysics · Physics 2024-02-23 Thomas Flöss , P. Daniel Meerburg

We develop a machine learning approach to reconstructing the cosmological initial conditions from late-time dark matter halo number density fields in redshift space, with the goal of improving sensitivity to cosmological parameters, and in…

Cosmology and Nongalactic Astrophysics · Physics 2025-08-15 Jelte Bottema , Thomas Flöss , P. Daniel Meerburg

Observations of galaxy clustering are made in redshift space, which results in distortions to the underlying isotropic distribution of galaxies. These redshift-space distortions (RSD) not only degrade important features of the matter…

Cosmology and Nongalactic Astrophysics · Physics 2020-07-29 Yuchan Wang , Baojiu Li , Marius Cautun

Reconstructing the density fluctuations in the early Universe that evolved into the distribution of galaxies we see today is a challenge of modern cosmology [ref.]. An accurate reconstruction would allow us to test cosmological models by…

Astrophysics · Physics 2015-06-24 Uriel Frisch , Sabino Matarrese , Roya Mohayaee , Andrei Sobolevski

The large scale structure of the universe is reconstructed by means of the Wiener filter and constrained realizations of Gaussian fields. The density field constructed from optically selected galaxies (Hudson \cite{Hudson}) has been sampled…

Astrophysics · Physics 2007-05-23 Y. Hoffman

Gravitational lensing distorts the cosmic microwave background (CMB) anisotropies and imprints a characteristic pattern onto it. The distortions depend on the projected matter density between today and redshift $z \sim 1100$. In this paper…

Astrophysics · Physics 2016-08-25 Matias Zaldarriaga , Uros Seljak

We use the physics of ellipsoidal collapse to model the probability distribution function of the smoothed dark matter density field in real and redshift space. We provide a simple approximation to the exact collapse model which shows…

Astrophysics · Physics 2008-08-05 Tsz Yan Lam , Ravi K. Sheth

A novel routine to investigate the scalar fields in a cosmological context is discussed in the framework of the Hamiltonian formalism. Starting from the Einstein-Hilbert action coupled to a Lagrangian density that contains two components -…

General Relativity and Quantum Cosmology · Physics 2013-09-16 Alex E. Bernardini , O. Bertolami

The gravitational coupling between large-scale perturbations and small-scale perturbations leads to anisotropic distortions of the small-scale matter distribution. The measured local small-scale power spectrum can thus be used to infer the…

Cosmology and Nongalactic Astrophysics · Physics 2022-04-20 Hong-Ming Zhu , Tian-Xiang Mao , Ue-Li Pen

We present a new Bayesian methodology to learn the unknown material density of a given sample by inverting its two-dimensional images that are taken with a Scanning Electron Microscope. An image results from a sequence of projections of the…

Applications · Statistics 2014-03-06 Dalia Chakrabarty , Fabio Rigat , Nare Gabrielyan , Richard Beanland , Shashi Paul

In this work we expand upon the Tomographic Absorption Reconstruction and Density Inference Scheme (TARDIS) in order to include multiple tracers while reconstructing matter density fields at Cosmic Noon (z ~ 2-3). In particular, we jointly…

Cosmology and Nongalactic Astrophysics · Physics 2021-02-26 Benjamin Horowitz , Benjamin Zhang , Khee-Gan Lee , Robin Kooistra

Simulating the evolution of the local universe is important for studying galaxies and the intergalactic medium in a way free of cosmic variance. Here we present a method to reconstruct the initial linear density field from an input…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 Huiyuan Wang , H. J. Mo , Xiaohu Yang , Y. P. Jing , W. P. Lin

This paper presents a stochastic approach to the clustering evolution of dark matter haloes in the Universe. Haloes, identified by a Press-Schechter-type algorithm in Lagrangian space, are described in terms of `counting fields', acting as…

Astrophysics · Physics 2009-10-30 P. Catelan , F. Lucchin , S. Matarrese , C. Porciani

The reconstruction algorithm introduced by \cite{Eis07}, which is widely used in clustering analysis, is based on the inference of the first order Lagrangian displacement field from the Gaussian smoothed galaxy density field in redshift…

Cosmology and Nongalactic Astrophysics · Physics 2016-12-09 M. Vargas-Magaña , S. Ho , S. Fromenteau , A. J. Cuesta

The peculiar velocities of dark matter halos are crucial to study many issues in cosmology and galaxy evolution. In this study, by using the state-of-the-art deep learning technique, a UNet-based neural network, we propose to reconstruct…

Cosmology and Nongalactic Astrophysics · Physics 2023-05-10 Ziyong Wu , Liang Xiao , Xu Xiao , Jie Wang , Xi Kang , Yang Wang , Xin Wang , Le Zhang , Xiao-Dong Li

The distribution of matter that is measured through galaxy redshift and peculiar velocity surveys can be harnessed to learn about the physics of dark matter, dark energy, and the nature of gravity. To improve our understanding of the matter…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-04 Fei Qin , David Parkinson , Sungwook E. Hong , Cristiano G. Sabiu

A crucial aspect of mass-mapping, via weak lensing, is quantification of the uncertainty introduced during the reconstruction process. Properly accounting for these errors has been largely ignored to date. We present a new method to…

Cosmology and Nongalactic Astrophysics · Physics 2021-12-16 Matthew A. Price , Jason D. McEwen , Xiaohao Cai , Thomas D. Kitching , Christopher G. R. Wallis

We derive and implement a full Bayesian large scale structure inference method aiming at precision recovery of the cosmological power spectrum from galaxy redshift surveys. Our approach improves over previous Bayesian methods by performing…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-16 Jens Jasche , Benjamin D. Wandelt
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