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Dark energy in the universe is assumed to be vacuum energy. The energy-momentum of vacuum is described by a scale-dependent cosmological constant. The equations of motion imply for the density of matter (dust) the sum of the usual matter…

General Physics · Physics 2008-11-09 Walter Petry

A physical mechanism that produces three energy components is proposed as the common origin of dark energy and dark matter. The first two have equations of state W ~ 0 and act like dark matter, while the last has W ~ -1 at low redshifts…

General Relativity and Quantum Cosmology · Physics 2012-12-12 I. Gontijo

The problem of dark energy is briefly reviewed in both theoretical and observational aspects. In the theoretical aspect, dark energy scenarios are classified into symmetry, anthropic principle, tuning mechanism, modified gravity, quantum…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-08 Miao Li , Xiao-Dong Li , Shuang Wang , Yi Wang

For the first time, we have a plausible, complete accounting of matter and energy in the Universe. Expressed a fraction of the critical density it goes like this: neutrinos, between 0.3% and 15%; stars, 0.5%; baryons (total), 5%; matter…

Astrophysics · Physics 2007-05-23 Michael S. Turner

For the first time, we have a plausible and complete accounting of matter and energy in the Universe. Expressed a fraction of the critical density it goes like this: neutrinos, between 0.3% and 15%; stars, between 0.3% and 0.6%; baryons…

Astrophysics · Physics 2009-10-31 Michael S. Turner

It is now well accepted that both Dark Matter and Dark Energy are required in any successful cosmological model. Although there is ample evidence that both Dark components are necessary, the conventional theories make no prediction for the…

Astrophysics · Physics 2007-05-23 Douglas Scott , Ali Frolop

An impressive amount of different astrophysical data converges towards the picture of a spatially flat universe undergoing a today phase of accelerated expansion. The nature of the dark energy dominating the energy content of the universe…

Astrophysics · Physics 2009-11-10 S. Capozziello , V. F. Cardone , M. Funaro , S. Andreon

The existence of dark matter and dark energy in cosmology is implied by various observations, however, they are still unclear because they have not been directly detected. In this Letter, an unified model of dark energy and dark matter that…

Cosmology and Nongalactic Astrophysics · Physics 2016-10-27 Jiro Matsumoto

A model concerning particle theory and cosmology is proposed. Matter field, dark matter and dark energy are created by an energy flow from space to primordial matter fields at the phase transition in the early universe.

General Physics · Physics 2024-10-08 Masayasu Tsuge

To explain the acceleration of the cosmological expansion researchers have considered an unusual form of mass-energy generically called dark energy. Dark energy has a ratio of pressure over mass density which obeys $w=p/\rho <-1/3$. This…

High Energy Physics - Theory · Physics 2008-12-19 Max Chaves , Douglas Singleton

A cosmological model of dark energy interacting with dark matter and another general component of the universe is investigated. We found general constraints on these models imposing an accelerated expansion. The same is also studied in the…

High Energy Physics - Phenomenology · Physics 2008-11-26 Norman Cruz , Samuel Lepe , Francisco Pena

The standard model of cosmology suggests the existence of two components, "dark matter" and "dark energy", which determine the fate of the Universe. Their nature is still under investigation, and no direct proof of their existences has…

Astrophysics · Physics 2009-07-09 A. Arbey

A model of cosmology, that arises from the hypothesis that ordinary matter, dark matter and dark energy are made of the same stuff, is studied. It is argued that this hypothesis is a consequence of considering space and time in the same…

Astrophysics · Physics 2007-05-23 Isaac Cohen

The cosmological concordance model contains two separate constituents which interact only gravitationally with themselves and everything else, the dark matter and the dark energy. In the standard dark energy models, the dark matter makes up…

Astrophysics · Physics 2008-11-26 Martin Kunz

Dark energy is one of the mysteries of modern science. It is unlike any known form of matter or energy and has been detected so far only by its gravitational effect of repulsion. Owing to its effects being discernible only at very very…

Cosmology and Nongalactic Astrophysics · Physics 2009-08-25 Aruna Kesavan

In this paper is proposed a geometric solution to the dark energy, assuming that the space can be divided into regions of size $\sim L_{p}$ and energy $\sim E_{p}$. Significantly this assumption generate a energy density similar to the…

General Relativity and Quantum Cosmology · Physics 2011-02-08 Miguel Angel García-Aspeitia

The consideration of dark energy's quanta, required also by thermodynamics, introduces its chemical potential into the cosmological equations. Isolating its main contribution, we obtain solutions with dark energy decaying to matter or…

Astrophysics · Physics 2008-11-26 J. Besprosvany

The nature of dark matter (DM) and dark energy (DE) which is supposed to constitute about 95% of the energy density of the universe is still a mystery. There is no shortage of ideas regarding the nature of both. While some candidates for DM…

General Physics · Physics 2017-08-25 Kenath Arun , S. B. Gudennavar , C Sivaram

We present three distinct types of models of dark energy in the form of a scalar field which is explicitly coupled to dark matter. Our construction draws from the pull-back formalism for fluids and generalises the fluid action to involve…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-11 A. Pourtsidou , C. Skordis , E. J. Copeland

In an introductory manner, the nature of dark energy is addressed, how it is observed and what further tests are needed to reconstruct its properties. Several theoretical approaches to dark energy will be discussed. Finally, the dark…

Astrophysics · Physics 2007-05-23 Paul H. Frampton
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