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Bulk viscosity has been intrinsically existing in the observational cosmos evolution with various effects for different cosmological evolution stages endowed with complicated cosmic media. Normally in the idealized "standard cosmology" the…

Cosmology and Nongalactic Astrophysics · Physics 2014-01-22 Jiaxin Wang , Xinhe Meng

After a short history of the $\Lambda$-term it is explained why the (effective) cosmological constant is expected to obtain contributions from short-distance physics, corresponding to an energy at least as large as the Fermi scale. The…

Astrophysics · Physics 2007-05-23 Norbert Straumann

We directly compare the concordance LCDM model to the inhomogeneous matter-only alternative represented by LTB void models. To achieve a "democratic" confrontation we explore LLTB models with non-vanishing cosmological constant and perform…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-24 Valerio Marra , Mikko Paakkonen

Cosmological parameters can be measured by comparing peculiar velocities with those predicted from a galaxy density field. Previous work has tested the accuracy of this approach with N-body simulations, but generally on idealised mock…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-27 Amber M. Hollinger , Michael J. Hudson

We present a cosmological model constituted by three perfect fluids, cold dark matter, vacuum energy and radiation, which interacting with each other lead to an equivalent model of three self-preserved fluids that can be identified with the…

General Relativity and Quantum Cosmology · Physics 2018-01-25 Mónica Forte

The role of Lorentz invariance as a fundamental symmetry of nature has been lately reconsidered in different approaches to quantum gravity. It is thus natural to study whether other puzzles of physics may be solved within these proposals.…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-15 B. Audren , D. Blas , J. Lesgourgues , S. Sibiryakov

The $\Lambda$CDM model provides a good fit to most astronomical observations but harbors large areas of phenomenology and ignorance. With the improvements in the precision and number of observations, discrepancies between key cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2023-02-15 Jian-Ping Hu , Fa-Yin Wang

Putting constraints on a possible Lorentz Invariance Violation (LIV) from astrophysical sources such as gamma-ray bursts (GRBs) is essential for finding evidences of new theories of quantum gravity (QG) that predict an energy-dependent…

General Relativity and Quantum Cosmology · Physics 2023-10-02 Denitsa Staicova

We propose an analytic procedure that allows to determine quantitatively the deviation in the behavior of cosmological perturbations between a given f(R) modified gravity model and a LCDM reference model. Our method allows to study…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 Daniele Bertacca , Nicola Bartolo , Sabino Matarrese

Current observations do not rule out the possibility that the Universe might end up in an abrupt event. Different such scenarios may be explored through suitable parameterizations of the dark energy and then confronted to cosmological…

Cosmology and Nongalactic Astrophysics · Physics 2024-03-22 R. Lazkoz , V. Salzano , L. Fernandez-Jambrina , M. Bouhmadi-López

We integrate $\Lambda_{\rm s}$CDM, a promising scenario for alleviating cosmological tensions, into VCDM, a type-II minimally modified gravity. This promotes the scenario to a fully predictive model (dubbed $\Lambda_{\rm s}$VCDM) that…

Cosmology and Nongalactic Astrophysics · Physics 2026-04-29 Özgür Akarsu , Antonio De Felice , Eleonora Di Valentino , Suresh Kumar , Rafael C. Nunes , Emre Özülker , J. Alberto Vazquez , Anita Yadav

The cosmic curvature $\Omega_{K}$ is an important parameter related to the inflationary cosmology and the ultimate fate of the universe. In this work, we adopt the non-CMB observations to constrain $\Omega_{K}$ in the $\Lambda$CDM model and…

Cosmology and Nongalactic Astrophysics · Physics 2025-09-12 Peng-Ju Wu , Xin Zhang

This paper is based on two insights: (1) that general relativity alone does not specify how much of the matter density contributes to the source term in Friedmann's equation, and how much contributes as the source of the gravitational…

General Relativity and Quantum Cosmology · Physics 2024-04-23 Richard J. Cook

Assessing the consistency of parameter constraints derived from different cosmological probes is an important way to test the validity of the underlying cosmological model. In an earlier work [Nicola et al., 2017], we computed constraints…

Cosmology and Nongalactic Astrophysics · Physics 2017-11-01 Andrina Nicola , Adam Amara , Alexandre Refregier

We analyse various low-redshift cosmological data from Type-Ia Supernova, Baryon Acoustic Oscillations, Time-Delay measurements using Strong-Lensing, $H(z)$ measurements using Cosmic Chronometers and growth measurements from large scale…

Cosmology and Nongalactic Astrophysics · Physics 2019-11-06 Koushik Dutta , Anirban Roy , Ruchika , Anjan A Sen , M. M. Sheikh-Jabbari

The Standard Model of cosmology, $\Lambda$CDM, while enormously successful, is currently unable to account for several cosmological anomalies the most prominent of which are in the measurements of the Hubble parameter and $S_8$.…

Cosmology and Nongalactic Astrophysics · Physics 2025-03-14 Amin Aboubrahim , Pran Nath

We describe inhomogeneities in a {\Lambda}CDM universe with a gradient series expansion and show that it describes the gravitational evolution far into the non-linear regime and beyond the capacity of standard perturbation theory at any…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-20 Gerasimos Rigopoulos , Wessel Valkenburg

Cosmography, as an integral branch of cosmology, strives to characterize the Universe without relying on pre-determined cosmological models. This model-independent approach utilizes Taylor series expansions around the current epoch,…

General Physics · Physics 2024-06-11 Seokcheon Lee

Creation of Cold Dark Matter (CCDM) can macroscopically be described by a negative pressure, and, therefore, the mechanism is capable to accelerate the Universe, without the need of an additional dark energy component. In this framework we…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-28 J. F. Jesus , F. A. Oliveira , S. Basilakos , J. A. S. Lima

Our intuitive understanding of cosmic structure formation works best in scales small enough so that bound, relaxed gravitating systems are no longer adjusting their radius; and large enough so that space and matter follow the average…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-17 Vasiliki Pavlidou , Theodore N. Tomaras
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