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Voids are promising cosmological probes. Nevertheless, every cosmological test based on voids must necessarily employ methods to identify them in redshift space. Therefore, redshift-space distortions (RSD) and the Alcock-Paczynski effect…

Cosmology and Nongalactic Astrophysics · Physics 2020-10-28 Carlos M. Correa , Dante J. Paz , Ariel G. Sánchez , Andrés N. Ruiz , Nelson D. Padilla , Raúl E. Angulo

After reviewing the cosmological constant problem - why is Lambda not huge? - I outline the two basic approaches that had emerged by the late 1980s, and note that each made a clear prediction. Precision cosmological experiments now indicate…

High Energy Physics - Theory · Physics 2007-05-23 Raphael Bousso

Void size function (VSF) contains information of the cosmic large-scale structure (LSS), and can be used to derive the properties of dark energy and dark matter. We predict the VSFs measured from the spectroscopic galaxy survey operated by…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-10 Yingxiao Song , Qi Xiong , Yan Gong , Furen Deng , Kwan Chuen Chan , Xuelei Chen , Qi Guo , Jiaxin Han , Guoliang Li , Ming Li , Yun Liu , Yu Luo , Wenxiang Pei , Chengliang Wei

Cosmology is living through fascinating times, where new observations from ground and space telescopes are questioning the established paradigm, the so-called Lambda Cold Dark Matter model. The particle nature of Dark Matter is severely…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-15 Juan Garcia-Bellido

We present a new and completely general technique for calculating the fine-grained phase-space structure of dark matter throughout the Galactic halo. Our goal is to understand this structure on the scales relevant for direct and indirect…

Astrophysics · Physics 2009-11-13 Mark Vogelsberger , Simon D. M. White , Amina Helmi , Volker Springel

The formation of large voids in the Cosmic Web from the initial adiabatic cosmological perturbations of space-time metric, density and velocity of matter is investigated in cosmological model with the dynamical dark energy accelerating…

Cosmology and Nongalactic Astrophysics · Physics 2017-04-04 B. Novosyadlyj , M. Tsizh

I briefly outline a new physical interpretation to the average cosmological parameters for an inhomogeneous universe with backreaction. The variance in local geometry and gravitational energy between ideal isotropic observers in bound…

Cosmology and Nongalactic Astrophysics · Physics 2009-12-31 David L. Wiltshire

This paper describes a method for quantitatively comparing an N-body model with a sample of discrete kinematic data. The comparison has two stages: (i) finding the optimum scaling and orientation of the model relative to the data; and (ii)…

Astrophysics · Physics 2009-10-30 Prasenjit Saha

Baryonic Acoustic Oscillations (BAOs) studies based on the clustering of voids and matter tracers provide important constraints on cosmological parameters related to the expansion of the Universe. However, modelling the void exclusion…

Cosmology and Nongalactic Astrophysics · Physics 2023-07-18 Andrei Variu , Cheng Zhao , Daniel Forero-Sánchez , Chia-Hsun Chuang , Francisco-Shu Kitaura , Charling Tao , Amélie Tamone , Jean-Paul Kneib

We compare the evolution of voids formed under the standard cosmological model and two alternative cosmological models. The two models are a quintessence model ($\phi$CDM) and a Coupled Dark Matter-Dark Energy (CDE) model, both of which…

Cosmology and Nongalactic Astrophysics · Physics 2018-08-01 Eromanga Adermann , Pascal J Elahi , Geraint F Lewis , Chris Power

LRS Bianchi type-I models have been studied in the cosmological theory based on Lyra's geometry. A new class of exact solutions has been obtained by considering a time dependent displacement field for variable deceleration parameter models…

General Relativity and Quantum Cosmology · Physics 2010-05-28 Anirudh Pradhan , D. S. Chauhan

Modern cosmological observations allow us to study in great detail the evolution and history of the large scale structure hierarchy. The fundamental problem of accurate constraints on the cosmological parameters, within a given cosmological…

Astrophysics · Physics 2009-11-13 K. Dolag , S. Borgani , S. Schindler , A. Diaferio , A. M. Bykov

We propose a novel approach for parameterizing the luminosity distance, based on the use of rational "Pad\'e" approximations. This new technique extends standard Taylor treatments, overcoming possible convergence issues at high redshifts…

General Relativity and Quantum Cosmology · Physics 2015-06-19 Alejandro Aviles , Alessandro Bravetti , Salvatore Capozziello , Orlando Luongo

We revise the cosmological standard model presuming that matter, i.e. baryons and cold dark matter, exhibits a non-vanishing pressure mimicking the cosmological constant effects. In particular, we propose a scalar field Lagrangian $\mathcal…

General Relativity and Quantum Cosmology · Physics 2018-11-28 Orlando Luongo , Marco Muccino

The universe content is considered as a non-perfect fluid with bulk viscosity and can be described by a general equation of state (endowed some deviation from the conventionally assumed cosmic perfect fluid model). An explicitly bulk…

Astrophysics · Physics 2009-10-16 X H Meng , X Dou

Approximations to the exact solutions for gravitational instability in the expanding Universe are extremely useful for understanding the evolution of large--scale structure. We report on a series of tests of Newtonian Lagrangian…

Astrophysics · Physics 2007-05-23 T. Buchert , A. L. Melott , A. G. Weiss

We explore the capability of deep learning to classify cosmic structures. In cosmological simulations, cosmic volumes are segmented into voids, sheets, filaments and knots, according to the distribution and kinematics of dark matter (DM),…

Astrophysics of Galaxies · Physics 2022-08-03 Shigeki Inoue , Xiaotian Si , Takashi Okamoto , Moka Nishigaki

We present a new definition of cosmic void and a publicly available code with the algorithm that implements it. Underdense regions are defined as free-form objects, called popcorn voids, made from the union of spheres of maximum volume with…

Cosmology and Nongalactic Astrophysics · Physics 2023-04-26 Dante J. Paz , Carlos M. Correa , Sebastián R. Gualpa , Andres N. Ruiz , Carlos S. Bederián , R. Dario Graña , Nelson D. Padilla

We study the nonlinear gravitational dynamics of a universe filled with a pressureless fluid and a cosmological constant $\Lambda$ in the context of Newtonian gravity, and in the relativistic post-Friedmann approach proposed in paper I [I.…

General Relativity and Quantum Cosmology · Physics 2016-10-26 Cornelius Rampf , Eleonora Villa , Daniele Bertacca , Marco Bruni

A generalization of the notion of ellipsoids to curved Riemannian spaces is given and the possibility to use it in describing the shapes of rotating bodies in general relativity is examined. As an illustrative example, stationary,…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Jozsef Zsigrai
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