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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

We present the linear inverse redshift space operator which maps the galaxy density field derived from redshift surveys from redshift space to real space. Expressions are presented for observers in both the CMBR and Local Group rest frames.…

Astrophysics · Physics 2009-10-31 Andy Taylor , Helen Valentine

We have developed a new geometrical method for identifying and reconstructing a homogeneous and highly complete set of galaxy groups in the next generation of deep, flux-limited redshift surveys. Our method combines information from the…

Astrophysics · Physics 2009-11-07 Christian Marinoni , Marc Davis , Jeffrey A. Newman , Alison L. Coil

We assess a neural network (NN) method for reconstructing 3D cosmological density and velocity fields (target) from discrete and incomplete galaxy distributions (input). We employ second-order Lagrangian Perturbation Theory to generate a…

Cosmology and Nongalactic Astrophysics · Physics 2023-06-02 Punyakoti Ganeshaiah Veena , Robert Lilow , Adi Nusser

The peculiar velocity field of the local Universe provides direct insights into its matter distribution and the underlying theory of gravity, and is essential in cosmological analyses for modelling deviations from the Hubble flow. Numerous…

Galaxies are biased tracers of the underlying cosmic web, which is dominated by dark matter components that cannot be directly observed. Galaxy formation simulations can be used to study the relationship between dark matter density fields…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-19 Victoria Ono , Core Francisco Park , Nayantara Mudur , Yueying Ni , Carolina Cuesta-Lazaro , Francisco Villaescusa-Navarro

Discovering the mass of neutrinos is a principle goal in high energy physics and cosmology. In addition to cosmological measurements based on two-point statistics, the neutrino mass can also be estimated by observations of neutrino wakes…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-08 Derek Inman , J. D. Emberson , Ue-Li Pen , Alban Farchi , Hao-Ran Yu , Joachim Harnois-Deraps

[abridge]Cosmic velocity and tidal fields are important for the understanding of the cosmic web and the environments of galaxies, and can also be used to constrain cosmology. In this paper, we reconstruct these two fields in SDSS volume…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Huiyuan Wang , H. J. Mo , Xiaohu Yang , Frank C. van den Bosch

Our goal is to recover the Galactic Halo spatial density by means of field stars. To this aim, we apply a new technique to the Capodimonte Deep Field (OACDF, Alcala' et al. 2004), as a pilot study in view of the VLT Survey Telescope (VST)…

Astrophysics · Physics 2009-11-11 M. Cignoni , V. Ripepi , M. Marconi , J. M. Alcala' , M. Capaccioli , M. Pannella , R. Silvotti

Spectroscopic redshift surveys are key tools to trace the large-scale structure (LSS) of the Universe and test the $\Lambda$CDM model. However, using redshifts as distance proxies introduces distortions in the 3D galaxy distribution. If…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-09 Edoardo Maragliano , Punyakoti Ganeshaiah Veena , Giulia Degni , Enzo Franco Branchini

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

For many analyses in cosmology it is necessary to reconstruct the likely distribution of unobserved fields, such as dark matter or non-luminous baryons, from observed luminous tracers. The dominant approach in cosmology has been to use the…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-16 Jordan Krywonos , Yurii Kvasiuk , Matthew C. Johnson , Moritz Münchmeyer

We reconstruct the 3D matter density and peculiar velocity fields in the local Universe up to a distance of 200$\,h^{-1}\,$Mpc from the Two-Micron All-Sky Redshift Survey (2MRS), using a neural network (NN). We employed an NN with a U-net…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-01 Robert Lilow , Punyakoti Ganeshaiah Veena , Adi Nusser

The COSMOS field has been the subject of a wide range of observations, with a number of studies focusing on reconstructing the 3D dark matter density field. Typically, these studies have focused on one given method or tracer. In this paper,…

We present a maximum probability approach to reconstructing spatial maps of the peculiar velocity field at redshifts $z\sim0.1$, where the velocities have been measured from distance indicators (DI) such as $D_n-\sigma$ relations or…

Cosmology and Nongalactic Astrophysics · Physics 2014-11-18 Russell Johnston , David Bacon , Luis F. A. Teodoro , Robert C. Nichol , Michael S. Warren , Catherine Cress

We present a method to reconstruct the initial linear-regime matter density field from the late-time non-linearly evolved density field in which we channel the output of standard first-order reconstruction to a convolutional neural network…

Cosmology and Nongalactic Astrophysics · Physics 2023-10-23 Christopher J. Shallue , Daniel J. Eisenstein

Cosmologists aim to model the evolution of initially low amplitude Gaussian density fluctuations into the highly non-linear "cosmic web" of galaxies and clusters. They aim to compare simulations of this structure formation process with…

Cosmology and Nongalactic Astrophysics · Physics 2021-05-05 Renan Alves de Oliveira , Yin Li , Francisco Villaescusa-Navarro , Shirley Ho , David N. Spergel

Direct measurements of peculiar velocities of galaxies and clusters of galaxies can in principle provide explicit information on the three dimensional mass distribution, but this information is modulated by the fact that velocity field is…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Teppei Okumura , Uros Seljak , Zvonimir Vlah , Vincent Desjacques

We discuss an implementation of a deep learning framework to gain insight into dark matter (DM) structure formation. We investigate the contribution of velocity and density field information to the construction of the halo mass function…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-13 Saba Etezad-Razavi , Erfan Abbasgholinejad , Mohammad-Hadi Sotoudeh , Farbod Hassani , Sadegh Raeisi , Shant Baghram

We present a novel way of using neural networks (NN) to estimate the redshift distribution of a galaxy sample. We are able to obtain a probability density function (PDF) for each galaxy using a classification neural network. The method is…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-08 Christopher Bonnett