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An oscillating universe cycles through a series of expansions and contractions. We propose a model in which ``phantom'' energy with a supernegative pressure ($p < - \rho$) grows rapidly and dominates the late-time expanding phase. The…

Astrophysics · Physics 2008-03-29 Katherine Freese , Matthew G. Brown , William H. Kinney

ecent observations of type Ia supernovae indicate that the Universe is in an accelerating phase of expansion. The fundamental quest in theoretical cosmology is to identify the origin of this phenomenon. In principle there are two…

Astrophysics · Physics 2014-10-13 Marek Szydlowski

We propose a cosmological model that makes a significant step toward solving the coincidence problem of the near similarity at the present of the dark energy and dark matter components. Our cosmology has the following properties: a) among…

Astrophysics · Physics 2008-11-26 Luca Amendola , Domenico Tocchini-Valentini

Modern astrophysical and cosmological models are faced with two severe theoretical difficulties, that can be summarized as the dark energy and the dark matter problems. Relative to the former, it has been stated that cosmology has entered a…

General Relativity and Quantum Cosmology · Physics 2013-08-23 Francisco S. N. Lobo

Accelerated expansion of the Universe may result from an anti-frictional force that is self-consistently exerted on cold dark matter (CDM). Cosmic anti-friction is shown to give rise to an effective negative pressure of the cosmic medium.…

Astrophysics · Physics 2009-11-07 Dominik J. Schwarz , Winfried Zimdahl , Alexander B. Balakin , Diego Pavon

By incorporating the holographic principle in a time-depending Lambda-term cosmology, new physical bounds on the arbitrary parameters of the model can be obtained. Considering then the dark energy as a purely geometric entity, for which no…

General Relativity and Quantum Cosmology · Physics 2009-11-11 J. P. Beltran Almeida , J. G. Pereira

The presence of dark energy in the Universe is inferred directly and indirectly from a large body of observational evidence. The simplest and most theoretically appealing possibility is the vacuum energy density (cosmological constant).…

Astrophysics · Physics 2008-11-26 J. S. Alcaniz

In the present work, we have studied the dynamics of accelerating universe considering a simple parametrization of the equation of state parameter in an interacting scenario. In this toy model, the dark energy component is allowed to…

General Relativity and Quantum Cosmology · Physics 2025-05-23 Sangita Goswami , Sudipta Das

We investigate the cosmological evolution of an interacting phantom energy model in which the phantom field has interaction with the dark matter. We discuss the existence and stability of scaling solutions for two types of specific…

Astrophysics · Physics 2007-05-23 Zong-Kuan Guo , Rong-Gen Cai , Yuan-Zhong Zhang

We have observed the acceleration of the expansion of the universe. To explain this phenomenon, we usually introduce the dark energy (DE) which has a negative pressure or we need to modify the Einstein's equation to produce a term which is…

Cosmology and Nongalactic Astrophysics · Physics 2011-11-04 Dong-Biao Kang

Astrophysical observations are pointing out huge amounts of dark matter and dark energy needed to explain the observed large scale structures and cosmic accelerating expansion. Up to now, no experimental evidence has been found, at…

Astrophysics · Physics 2009-11-11 S. Capozziello , V. F. Cardone , A. Troisi

Recent observations of the Universe have led to a conclusion suppressing an up-to-now supposed deceleration of the Universe caused by attractive gravitational forces. Contrary, there is a renaissance of the cosmological member lambda and…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Jozef Sima , Miroslav Sukenik

Motivated by the recent observations for the cosmic acceleration and the suitable evolution of the Universe provided an interaction (decay of dark energy to matter) is incorporated in a cosmological model, we study the cosmological…

High Energy Physics - Theory · Physics 2009-03-24 M. R. Setare , Elias C. Vagenas

We work on the reconstruction scenario of pilgrim dark energy" (PDE) in $f(T, T_G)$. In PDE model it is assumed that a repulsive force that is accelerating the Universe is phantom type with $(w_{DE}<-1)$ and it so strong that prevents…

General Relativity and Quantum Cosmology · Physics 2018-10-09 Surajit Chattopadhyay , Abdul Jawad , Davood Momeni , Ratbay Myrzakulov

In the present work, an alternative interpretation of the source of accelerated expansion of the Universe is suggested. A probable candidate is the interaction between the quantum spin of a moving particle and the torsion of space-time,…

General Relativity and Quantum Cosmology · Physics 2016-11-15 M. I. Wanas

We explore a model of interacting dark energy where the dark energy density is related by the holographic principle to the Hubble parameter, and the decay of the dark energy into matter occurs at a rate comparable to the current value of…

Astrophysics · Physics 2008-12-18 Micheal S. Berger , Hamed Shojaei

The physical nature of the presently dominating enigmatic dark energy in the expanding universe is demonstrated to be explainable as an excess of the kinetic energy with respect to its potential energy. According to traditional Friedman…

Cosmology and Nongalactic Astrophysics · Physics 2018-03-14 Arved Sapar

Using the evolution history of the universe, one can make constraint on the parameter space of dynamic dark energy models. We discuss two different parameterized dark energy models. Our results further restrict the combined constraints…

Astrophysics · Physics 2009-11-13 Zhuo-Yi Huang , Bin Wang , Rong-Gen Cai , Ru-Keng Su

The traditional "explanation" for the observed acceleration of the universe is the existence of a positive cosmological constant. However, this can hardly be a truly convincing explanation, as an expanding universe is not expected to have a…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Joan Sola

Dark Energy is some of the weirdest and most mysterious stuff in the universe that tends to increase the rate of expansion of the universe. Two commonly known forms of dark energy are the cosmological constant, a constant energy density…

General Relativity and Quantum Cosmology · Physics 2010-04-28 Ishwaree P. Neupane , Holly Trowland