scholarly journals Interactions in the dark sector of the Universe

2014 ◽  
Vol 11 (02) ◽  
pp. 1460014 ◽  
Author(s):  
Winfried Zimdahl
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Dark Sector ◽  
Future Evolution ◽  
Evolution Of The Universe ◽  
Λcdm Model ◽  
The Future ◽  
The Universe

Interactions inside the cosmological dark sector influence the cosmological dynamics. As a consequence, the future evolution of the Universe may be different from that predicted by the ΛCDM model. We review main features of several recently studied models with nongravitational couplings between dark matter and dark energy.

scholarly journals Cosmology from multimeasure multifield model

2019 ◽  
Vol 34 (19) ◽  
pp. 1950099 ◽  
Author(s):  
Denitsa Staicova ◽  
Michail Stoilov
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Model Potential ◽  
Higgs Mechanism ◽  
Evolution Of The Universe ◽  
Slow Roll ◽  
Cosmological Application ◽  
Proposed Model ◽  
Model Setup ◽  
The Universe

We consider the cosmological application of a (variant of) relatively newly proposed model1 unifying inflation, dark energy, dark matter, and the Higgs mechanism. The model was originally defined using additional non-Riemannian measures, but it can be reformulated into effective quintessential model unifying inflation, dark energy and dark matter. Here, we demonstrate numerically that it is capable of describing the entire evolution of the Universe in a seamless way, but this requires some revision of the model setup. The main reason is that there is a strong effective friction in the model, a feature which has been neglected in the pioneer work. This improves the model potential for proper description of the evolution of the Universe, because the friction ensures a finite time inflation with dynamically maintained low-value slow-roll parameters in the realistic scenarios. In addition, the model predicts the existence of a constant scalar field in late Universe.

scholarly journals THE UNIFIED EQUATION OF STATE FOR DARK MATTER AND DARK ENERGY

2005 ◽  
Vol 20 (19) ◽  
pp. 1443-1449 ◽  
Author(s):  
WEI WANG ◽  
YUANXING GUI ◽  
SUHONG ZHANG ◽  
GUANGHAI GUO ◽  
YING SHAO
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Equation Of State ◽  
Special Function ◽  
Simple Analysis ◽  
Evolution Of The Universe ◽  
Big Rip ◽  
The Universe

We assume that dark matter and dark energy satisfy the unified equation of state: p = B(z)ρ, with p = pdE, ρ = ρdm+ρdE, where the pressure of dark matter pdm = 0 has been taken into account. A special function [Formula: see text] is presented, which can well describe the evolution of the universe. In this model, the universe will end up with a Big Rip. By further simple analysis, we know other choices of the function B can also describe the universe but lead to a different doomsday.

scholarly journals The Λ and the CDM as Integration Constants

Symmetry ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2076
Author(s):  
Priidik Gallagher ◽  
Tomi Koivisto
Keyword(s):  
Dark Matter ◽  
Gauge Theory ◽  
Symmetry Breaking ◽  
Cosmological Constant ◽  
Spontaneous Symmetry Breaking ◽  
First Principles ◽  
Cold Dark Matter ◽  
Dark Sector ◽  
Λcdm Model ◽  
The Universe

Notoriously, the two main problems of the standard ΛCDM model of cosmology are the cosmological constant Λ and the cold dark matter, CDM. This essay shows that both the Λ and the CDM arise as integration constants in a careful derivation of Einstein’s equations from first principles in a Lorentz gauge theory. The dark sector of the universe might only reflect the geometry of a spontaneous symmetry breaking that is necessary for the existence of spacetime and an observer therein.

scholarly journals A quantum theory of spacetime in spinor formalism and the physical reality of cross-ratio representation: the equation of density parameters of dark energy, matter, and ordinary matter is derived: ΩM2 = 4 Ωb ΩΛ

2016 ◽  
Author(s):  
Jackie Liu
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Friedmann Equation ◽  
Physical Reality ◽  
Cross Ratio ◽  
Mathematical Relationship ◽  
Ordinary Matter ◽  
Evolution Of The Universe ◽  
Spinor Formalism ◽  
The Universe

ABSTRACT By theorizing the physical reality through the deformation of an arbitrary cross-ratio, we leverage Galois differential theory to describe the dynamics of isomonodromic integratable system. We found a new description of curvature of spacetime by the equivalency of isomonodromic integratable system and Penrose’s spinor formalism of general relativity. Using such description, we hypothetically quantize the curvature of spacetime (gravity) and apply to the problem of the evolution of the universe. The Friedmann equation is recovered and compared so that the mathematical relationship among dark energy, matter (dark matter + ordinary matter), and ordinary matter, ΩM2≃4ΩbΩΛ, is derived; the actual observed results are compared to this equation (calculated ΩM = 0.33 vs. observed ΩM = 0.31); the model might explain the origin of dark energy and dark matter of the evolution of the universe.

scholarly journals Cosmological evolution with interaction between dark energy and dark matter

2015 ◽  
Vol 24 (03) ◽  
pp. 1530007 ◽  
Author(s):  
Yuri L. Bolotin ◽  
Alexander Kostenko ◽  
Oleg A. Lemets ◽  
Danylo A. Yerokhin
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Holographic Dark Energy ◽  
Main Task ◽  
Nonlinear Interactions ◽  
Dark Sector ◽  
Standard Cosmological Model ◽  
Linear And Nonlinear ◽  
The Universe

In this review we consider in detail different theoretical topics associated with interaction in the dark sector. We study linear and nonlinear interactions which depend on the dark matter and dark energy densities. We consider a number of different models (including the holographic dark energy and dark energy in a fractal universe), with interacting dark energy and dark matter, have done a thorough analysis of these models. The main task of this review was not only to give an idea about the modern set of different models of dark energy, but to show how much can be diverse dynamics of the universe in these models. We find that the dynamics of a universe that contains interaction in the dark sector can differ significantly from the Standard Cosmological Model.

scholarly journals Interacting Dark Matter andq-Deformed Dark Energy Nonminimally Coupled to Gravity

2016 ◽  
Vol 2016 ◽  
pp. 1-17
Author(s):  
Emre Dil
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Field ◽  
Theoretical Description ◽  
Late Time ◽  
Dynamical Structure ◽  
Dark Sector ◽  
Accelerating Expansion ◽  
Stable Attractor ◽  
The Universe

In this paper, we propose a new approach to study the dark sector of the universe by considering the dark energy as an emergingq-deformed bosonic scalar field which is not only interacting with the dark matter, but also nonminimally coupled to gravity, in the framework of standard Einsteinian gravity. In order to analyze the dynamic of the system, we first give the quantum field theoretical description of theq-deformed scalar field dark energy and then construct the action and the dynamical structure of this interacting and nonminimally coupled dark sector. As a second issue, we perform the phase-space analysis of the model to check the reliability of our proposal by searching the stable attractor solutions implying the late-time accelerating expansion phase of the universe.

scholarly journals BAYESIAN ANALYSIS OF THE CHAPLYGIN GAS AND COSMOLOGICAL CONSTANT MODELS USING THE SNe Ia DATA

2004 ◽  
Vol 13 (04) ◽  
pp. 669-693 ◽  
Author(s):  
R. COLISTETE ◽  
J. C. FABRIS ◽  
S. V. B. GONÇALVES ◽  
P. E. DE SOUZA
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Confidence Level ◽  
Cold Dark Matter ◽  
Chaplygin Gas ◽  
Type Ia Supernovae ◽  
Λcdm Model ◽  
Type Ia ◽  
Ia Supernovae ◽  
The Universe

The type Ia supernovae observational data are used to estimate the parameters of a cosmological model with cold dark matter and the Chaplygin gas. This exotic gas, which is characterized by a negative pressure varying with the inverse of density, represents in this model the dark energy responsible for the acceleration of the Universe. The Chaplygin gas model depends essentially on four parameters: the Hubble constant, the velocity of the sound of the Chaplygin gas, the curvature of the Universe and the fraction density of the Chaplygin gas and the cold dark matter. The Bayesian parameter estimation yields [Formula: see text] and [Formula: see text]. These and other results indicate that a Universe completely dominated by the Chaplygin gas is favoured, what reinforces the idea that the Chaplygin gas may unify the description for dark matter and dark energy, at least as the type Ia supernovae data are concerned. A closed and accelerating Universe is also favoured. The Bayesian statistics indicates that the Chaplygin gas model is more likely than the standard cosmological constant (ΛCDM) model at 55.3% confidence level when an integration on all free parameters is performed. Assuming the spatially flat curvature, this percentage mounts to 65.3%. On the other hand, if the density of dark matter is fixed at zero value, the Chaplygin gas model becomes more preferred than the ΛCDM model at 91.8% confidence level. Finally, the hypothesis of flat Universe and baryonic matter (Ωb0=0.04) implies a Chaplygin gas model preferred over the ΛCDM at a confidence level of 99.4%.

scholarly journals The building blocks of the universe

2021 ◽  
Vol 77 (3) ◽  
Author(s):  
Anslyn J. John
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Building Blocks ◽  
Big Bang ◽  
The State ◽  
Dark Sector ◽  
Big Bang Nucleosynthesis ◽  
Ordinary Matter ◽  
Special Collection ◽  
The Universe

I review the state of knowledge of the composition of the universe for a non-specialist audience. The universe is built up of four components. These are radiation, baryonic (ordinary) matter, dark matter and dark energy. In this article, a quick outline of the theory of Big Bang nucleosynthesis is presented, and the origin of the elements is explained. Cosmology requires the presence of dark matter, which forms most of the mass of the universe, and dark energy, which drives the acceleration of the expansion. The dark sector is motivated, and possible explanations are stated.Contribution: As part of this special collection on building blocks, the building blocks of the universe are discussed and unsolved problems and proposed solutions are highlighted.

scholarly journals Astromechanics of Dual Universe: A New Possible Explanation for the Universe Unsolved Problems

2020 ◽  
Author(s):  
Mohammed B. Al-Fadhli
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Hubble Parameter ◽  
Polar Coordinates ◽  
Accelerated Expansion ◽  
Dark Side ◽  
Second Phase ◽  
Spatial Curvature ◽  
Evolution Of The Universe ◽  
The Universe

The necessity of the dark energy and dark matter in the present universe could be a consequence of the antimatter elimination assumption in the early universe. Current cosmological models that rely on the dark side have left many unsolved mysteries, remarkably: tension in Hubble parameter measurements, the accelerated expansion, the fast orbital speed of stars, the dark flow observations, cosmic horizon, space flatness, absent of the antimatter, etc. On the other hand, General Relativity (GR) has relied on the spacetime to demonstrate the movement of matter due to a local curvature caused by the presence of matter. Founded on this, I trace the evolution of the spacetime worldlines based on the evolution of the universe spatial scale factor and its evolution time in polar coordinates in order to construct a potential spatial curvature over the temporal dimension or a global spacetime curvature. The mathematical derivations of a positively curved universe governed by only gravity revealed two opposite solutions of the worldline evolution. This possibly implies that the matter and antimatter could be evolving in opposite directions as distinct sides of the universe. By implementing the derived model, we find a decelerated phase of spatial expansion during the first 10 Gyr, that is followed by a second phase of an accelerated expansion; potentially matching the tension in Hubble parameter measurements. In addition, the model predicts a final time-reversal phase of spatial contraction, due to rapid surge in density i.e. reversal entropy, leading to a Big Crunch of a cyclic universe. The predicted density is 1.14. Other predictions are (1) an evolvable curved spacetime at the decelerated phase that is transformed to flatness at the accelerated phase with internal voids which could continuously increase the matter and antimatter densities elsewhere in both sides. (2) the spatial curvature through time dimension along spacetime worldlines was found to increase galaxy orbital speed and (3) a calculable flow rate of the matter side towards the antimatter side at the accelerated phase; conceivably explaining the dark flow observation. These findings may indicate the existence of the antimatter as a distinct side, which influences the evolution of the universe instead of the dark energy or dark matter. These theoretical outcomes and predictions are promising, which can be verified, fine-tuned or disproved using astrometric data in future works.

Viscous Ricci dark energy and generalized second law of thermodynamics in modified f(R, T) gravity

2018 ◽  
Vol 33 (38) ◽  
pp. 1850225 ◽  
Author(s):  
C. P. Singh ◽  
Ajay Kumar
Keyword(s):  
Dark Energy ◽  
Apparent Horizon ◽  
Second Law Of Thermodynamics ◽  
Second Law ◽  
Fluid Viscosity ◽  
Ricci Dark Energy ◽  
Evolution Of The Universe ◽  
Generalized Second Law ◽  
The Future ◽  
The Universe

The motivation of this paper is to study the bulk viscosity effect in Ricci dark energy (RDE) model within the framework of modified f(R, T) gravity, where R is the Ricci scalar and T is the trace of the energy–momentum tensor. As most studies assume that the universe is filled with a perfect fluid, viscosity is expected to present at least during some stages, especially in the early stage of the evolution of the universe but it could still become significant in the future. We assume the universe is filled with viscous RDE and pressureless dark matter. We consider the total bulk viscous coefficient is in the form of [Formula: see text][Formula: see text]H, where [Formula: see text] and [Formula: see text] are the constants. We obtain the solutions to the modified field equations by assuming a form f(R, T) = R [Formula: see text] T, where [Formula: see text] is a constant. We find the scale factor and deceleration parameter, and classify all possible evolutions of the universe. We briefly discuss the future finite-time singularity and show that the Big Rip singularity appears in viscous RDE model. We investigate two geometrical diagnostics, statefinder parameter and Om to analyze the dynamics of evolution of the universe. The trajectories of statefinder parameter reveal that the model behaves like quintessence for small [Formula: see text], and for large [Formula: see text] it shows the Chaplygin gas-like. However, in late time both the models approach [Formula: see text]CDM. The model shows a transition from decelerated phase to accelerated phase. Similarly, the Om analysis reveals that the model behaves like quintessence for small [Formula: see text] and phantom-like for large [Formula: see text]. We extend our study to analyze the time evolution of the total entropy and generalized second law of thermodynamics of viscous RDE model in f(R, T) theory inside the apparent horizon. Our study shows that the generalized second law of thermodynamics always preserves in viscous RDE model in a region enclosed by the apparent horizon under the suitable constraints of viscous coefficients.

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