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The standard procedure to explain the accelerated expansion of the Universe is to assume the existence of an exotic component with negative pressure, generically called dark energy. Here, we propose a new accelerating flat cosmology without…

Cosmology and Nongalactic Astrophysics · Physics 2025-02-21 P. W. R. Lima , J. A. S. Lima , J. F. Jesus

There is something unknown in the cosmos. Something big. Which causes the acceleration of the Universe expansion, that is perhaps the most surprising and unexpected discovery of the last decades, and thus represents one of the most pressing…

General Physics · Physics 2013-04-18 M. Villata

A phenomenological formalism is presented in which the apparent acceleration of the universe is generated by cosmic structure formation, without resort to Dark Energy, modifications to gravity, or a local void. The observed acceleration…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-05 Brett Bochner

The interacting dark matter (IDM) scenario allows for the acceleration of the Universe without Dark Energy. We constrain the IDM model by using the newly revised observational data including $H(z)$ data and Union2 SNe Ia via the Markov…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Shuo Cao , Zong-Hong Zhu , Nan Liang

We study the growth of perturbations in an expanding Newtonian universe with Bose-Einstein condensate dark matter. We first ignore special relativistic effects and derive a differential equation governing the evolution of the density…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-27 Pierre-Henri Chavanis

The Friedmann equation, augmented with an additional term that effectively takes on the role of dark energy, is demonstrated to be an exact solution to the recently proposed gravitational theory named "conformal Killing gravity." This…

General Relativity and Quantum Cosmology · Physics 2023-11-20 Junpei Harada

In the framework of Kaluza-Klein theory, we investigate a $(4+1)$-dimensional universe consisting of a $(4+1)$ dimensional Robertson-Walker type metric coupled with a $(4+1)$ dimensional energy-momentum tensor. The matter part consists of…

General Relativity and Quantum Cosmology · Physics 2015-05-13 F. Darabi

We investigate the interaction between dark energy and dark matter in the framework of irreversible thermodynamics of open systems with matter creation/annihilation. We consider dark energy and dark matter as an interacting two component…

General Relativity and Quantum Cosmology · Physics 2013-02-08 Tiberiu Harko , Francisco S. N. Lobo

The discovery ten years ago that the expansion of the Universe is accelerating put in place the present cosmological model, in which the Universe is composed of 4% baryons, 20% dark matter, and 76% dark energy. Yet the underlying cause of…

Cosmology and Nongalactic Astrophysics · Physics 2009-04-17 Joshua A. Frieman

A Friedmann like cosmological model in Einstein-Cartan framework is studied when the torsion function is assumed to be proportional to a single $\phi(t)$ function coming just from the spin vector contribution of ordinary matter. By…

General Relativity and Quantum Cosmology · Physics 2019-11-21 S. H. Pereira , R. de C. Lima , J. F. Jesus , R. F. L. Holanda

The fact that the LambdaCDM model fits the observations does not necessarily imply the physical existence of `dark energy'. Dropping the assumption that cold dark matter (CDM) is a perfect fluid opens the possibility to fit the data without…

Astrophysics · Physics 2007-05-23 Dominik J. Schwarz

Velocity-dependent interactions in a fundamental-string dominated universe lead quite naturally, with reasonable assumptions on initial conditions, to an accelerating expanding universe without assuming the existence of a cosmological…

Astrophysics · Physics 2009-11-07 Ramzi R. Khuri

Massive particle and antiparticle pair production and oscillation on the horizon form a holographic and massive pair plasma state in the Friedman Universe. Via this state, the Einstein cosmology term (dark energy) interacts with matter and…

General Relativity and Quantum Cosmology · Physics 2024-05-21 She-Sheng Xue

We derive the radial acceleration of stars in galaxies by using basic features of thermodynamics, statistical mechanics and general relativity. We assume that the "dark" component of the radial acceleration is originated from the reaction…

General Relativity and Quantum Cosmology · Physics 2019-04-18 Matteo Tuveri , Mariano Cadoni

In this paper we study new cosmological models involving new forms of non-gravitational interaction between cold dark matter and dark energy. The main purpose is to demonstrate the applicability of the forms of interaction to the problem in…

General Relativity and Quantum Cosmology · Physics 2017-08-09 Martiros Khurshudyan , Asatur Khurshudyan

We investigate cosmological constraints on an energy density contribution of elastic dark matter self-interactions characterized by the mass of the exchange particle and coupling constant. Because of the expansion behaviour in a…

Cosmology and Nongalactic Astrophysics · Physics 2010-06-17 Rainer Stiele , Tillmann Boeckel , Jürgen Schaffner-Bielich

It is shown that the Newton's law of universal gravitation can be derived from first submicroscopic principles inherent in the very nature of real space that is constituted as a tessellattice of primary topological balls. The submicroscopic…

General Physics · Physics 2016-09-21 Vlodymyr Krasnoholovets

Non-gravitational interaction between dark matter and dark energy has been considered in a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker (FLRW) universe. The interaction rate is assumed to be linear in the energy densities of dark…

General Relativity and Quantum Cosmology · Physics 2020-07-07 Supriya Pan , Jaume de Haro , Weiqiang Yang , Jaume Amorós

Detailed observations of the temperature fluctuations in the microwave background radiation indicate that we live in an open universe. From the size of these fluctuations it is concluded that the geometry of the universe is quite close to…

Astrophysics · Physics 2009-11-07 Selcuk Bayin

We argue that the conjectured dark mater in the Universe may be endowed with a new kind of gravitational charge that couples to a short range gravitational interaction mediated by a massive vector field. A model is constructed that…

General Relativity and Quantum Cosmology · Physics 2010-11-30 R. W. Tucker , C. Wang
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