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Related papers: Revisiting Ryskin's Model of Cosmic Acceleration

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In this article, we investigate the observed cosmic acceleration in the framework of a cosmological $f(R,L_m)$ model dominated by bulk viscous matter in an anisotropic background. We consider the LRS Bianchi type I metric and derive the…

General Relativity and Quantum Cosmology · Physics 2023-06-14 Raja Solanki , Bina Patel , Lakhan V. Jaybhaye , P. K. Sahoo

We discuss the problem of universe acceleration driven by global rotation. The redshift-magnitude relation is calculated and discussed in the context of SN Ia observation data. It is shown that the dynamics of considered problem is…

Astrophysics · Physics 2008-07-22 Wlodzimierz Godlowski , Marek Szydlowski

In a recent note (arXiv:1012.5069), the investigation performed by the present authors on the evolution of density fluctuations in an accelerated universe including matter creation was criticized. The criticism is based on the fact that the…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-30 Alain de Roany , J. A. de Freitas Pacheco

In the late Universe, and on cosmological scales, dark matter is conventionally assumed to be collisionless, as a consequence of the strong existing bounds on dark matter interactions at the Cosmic Microwave Background last-scattering…

Cosmology and Nongalactic Astrophysics · Physics 2026-03-11 Eugenia Dallari , Francesco Castagna , Emanuele Castorina , Maria Archidiacono , Ennio Salvioni

We consider a possible connection between matter and cosmological constant $\Lambda$ via the Newtonian cosmic potential of the matter within the expanding particle horizon. Consistent with GR, an increasing potential may drive the metric…

General Physics · Physics 2014-05-30 Herman Telkamp

Proposed in this paper is a possible interaction which exists in nature - inertial interaction. It gives matter an inertia and inertial mass. The formula of inertial mass has been derived. It is possible that inertial interaction leads to…

General Physics · Physics 2012-10-25 Xuejun Yang

This study investigates the emergence of dark energy during the matter-dominated era through spontaneous cosmological scalarization in the scalar-Ricci-Gauss-Bonnet model.Our model aligns with the conjecture that the speed of gravitational…

General Relativity and Quantum Cosmology · Physics 2025-07-31 H. Mohseni Sadjadi

We present an overview of a recently suggested new model of quantum initial conditions for the Universe in the form of a cosmological density matrix. This density matrix originally suggested in the Euclidean quantum gravity framework turns…

High Energy Physics - Theory · Physics 2008-11-03 A. O. Barvinsky , C. Deffayet , A. Yu. Kamenshchik

Recent observations of the luminosity-redshift in Type Ia supernovae suggest an accelerated inflation of the Universe (open Universe) as well as the observed matter density showed to be less than the critical one, suggesting that a large…

Astrophysics · Physics 2007-05-23 C. E. Navia , C. R. A. Augusto , D. F. Franceschini , K. H. Tsui

Recent observations indicate that the Universe is not transparent but partially opaque due to absorption of light by ambient cosmic dust. This implies that the Friedmann equations valid for the transparent universe must be modified for the…

General Physics · Physics 2022-06-06 Václav Vavryčuk

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

A model of the density distribution in the intergalactic medium, motivated by that found in numerical simulations, is used to demonstrate the effect of a clumpy IGM and discrete sources on the reionization of the universe. In an…

Astrophysics · Physics 2009-10-31 Jordi Miralda-Escude , Martin Haehnelt , Martin J. Rees

We use cosmological perturbation theory to study the backreaction effects of a self-consistent and well-defined cosmological averaging on the dynamics and the evolution of the Universe. Working with a perturbed…

General Relativity and Quantum Cosmology · Physics 2013-10-30 Iain A. Brown , Alan A. Coley , D. Leigh Herman , Joey Latta

The basic aim of this manuscript is to investigate the cosmological solutions in the context of the modified $f(R, T)$ theory of gravity, where $R$ is the Ricci scalar and $T$ is the trace of the energy-momentum tensor. For our current…

General Relativity and Quantum Cosmology · Physics 2024-03-26 Adnan Malik , Tayyaba Naz , Aimen Rauf , M. Farasat Shamir , Z. Yousaf

Phenomena currently attributed to Dark Matter (DM) and Dark Energy (DE) are merely a result of the interplay between gravitational energy density, caused by the contraction of space by matter, and space dilation, caused by the energy…

Astrophysics · Physics 2008-10-23 Shlomo Barak , Elia M. Leibowitz

A solution to Einstein's field equations via the Friedman equations is shown to produce a cosmological model that is in exact agreement with the measurements made by the dark energy astronomers. All the essential physical parameters are…

General Physics · Physics 2012-06-26 James G. Gilson

The recent observational evidence for the current cosmic acceleration have stimulated renewed interest in alternative cosmologies, such as scenarios with interaction in the dark sector (dark matter and dark energy). In general, such models…

Cosmology and Nongalactic Astrophysics · Physics 2009-10-22 R. S. Goncalves , J. S. Alcaniz , A. Dev , D. Jain

The viscosity of dark matter in cosmological models may cause an accelerated expansion and when this effect is sufficiently large, it can explain the dark energy. In this work, attributing the origin of viscosity to self-interaction of dark…

Cosmology and Nongalactic Astrophysics · Physics 2019-02-27 Abhishek Atreya , Jitesh R. Bhatt , Arvind Kumar Mishra

In this paper we discuss the properties of the quasi-steady state cosmological model (QSSC) developed in 1993 in its role as a cyclic model of the universe driven by a negative energy scalar field. We discuss the origin of such a scalar…

Astrophysics · Physics 2015-05-13 Jayant V. Narlikar , Geoffrey Burbidge , R. G. Vishwakarma

We calculate the back reaction of cosmological perturbations on a general relativistic variable which measures the local expansion rate of the Universe. Specifically, we consider a cosmological model in which matter is described by a single…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ghazal Geshnizjani , Robert Brandenberger
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