Probing the coupling between dark components of the universe

Guo, Zong Kuan; Ohta, Nobuyoshi; Tsujikawa, Shinji

doi:10.1103/physrevd.76.023508

Cited by 387 publications

(346 citation statements)

References 111 publications

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“…The addition of a non-linear function of the Ricci scalar R to the Einstein-Hilbert action has been demonstrated to cause acceleration for a wide variety of f (R) functions [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,…”

Section: Introductionmentioning

confidence: 99%

Models off(R)cosmic acceleration that evade solar system tests

2007

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We study a class of metric-variation f (R) models that accelerates the expansion without a cosmological constant and satisfies both cosmological and solar-system tests in the small-field limit of the parameter space. Solar-system tests alone place only weak bounds on these models, since the additional scalar degree of freedom is locked to the high-curvature general-relativistic prediction across more than 25 orders of magnitude in density, out through the solar corona. This agreement requires that the galactic halo be of sufficient extent to maintain the galaxy at high curvature in the presence of the low-curvature cosmological background. If the galactic halo and local environment in f (R) models do not have substantially deeper potentials than expected in ΛCDM, then cosmological field amplitudes |fR| 10 −6 will cause the galactic interior to evolve to low curvature during the acceleration epoch. Viability of large-deviation models therefore rests on the structure and evolution of the galactic halo, requiring cosmological simulations of f (R) models, and not directly on solar-system tests. Even small deviations that conservatively satisfy both galactic and solar-system constraints can still be tested by future, percent-level measurements of the linear power spectrum, while they remain undetectable to cosmological-distance measures. Although we illustrate these effects in a specific class of models, the requirements on f (R) are phrased in a nearly model-independent manner.

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Section: Introductionmentioning

confidence: 99%

Models off(R)cosmic acceleration that evade solar system tests

2007

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“…The lower b 2 , the closer the evolution of the Universe to a non-interacting model is. It should be emphasized that this phenomenological description has proven viable when contrasted with observations, i.e., SNIa, CMB, large scale structure, H(z), and age constraints [8,9,14,18], and recently in galaxy clusters [16,17].…”

mentioning

confidence: 99%

“…Indeed, it was shown that the coupling is small but positive which indicates that DE may decay into DM. Nevertheless, albeit the interaction hypothesis is gaining ground the observational limits on the strength of the coupling remain weak [18].…”

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confidence: 99%

Thermodynamical description of the interaction between holographic dark energy and dark matter

et al. 2008

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We present a thermodynamical description of the interaction between holographic dark energy and dark matter. If holographic dark energy and dark matter evolve separately, each of them remains in thermodynamic equilibrium. A small interaction between them may be viewed as a stable thermal fluctuation that brings a logarithmic correction to the equilibrium entropy. From this correction we obtain a physical expression for the interaction which is consistent with phenomenological descriptions and passes reasonably well the observational tests.

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“…In order to do this the model must successfully reproduce some important cosmological scenarios considered before in standard cosmology. For example, FRW cosmologies filled with a single fluid ρ with equation of state p = ωρ have an energy density of the form ρ = ρ 0 a −3(ω+1) , and those with two non-interacting fluids, as we have seen above, have the energy densities given by (7). Another type of FRW cosmologies, which provides us with a way to approach the coincidence problem, has energy densities which scale exactly as powers of the scale factor, so they are considered to be given by ρ 1 = ρ 10 a α and ρ 2 = ρ 20 a β in order to have ρ 1 /ρ 2 ∼ a const .…”

Section: Field Equations For Two Fluid Componentsmentioning

confidence: 99%

On a class of scaling FRW cosmological models

Cataldo¹,

Arevalo²,

Minning³

2010

J. Cosmol. Astropart. Phys.

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We study Friedmann-Robertson-Walker cosmological models with matter content composed of two perfect fluids ρ1 and ρ2, with barotropic pressure densities p1/ρ1 = ω1 = const and p2/ρ2 = ω2 = const, where one of the energy densities is given by ρ1 = C1a α + C2a β , with C1, C2, α and β taking constant values. We solve the field equations by using the conservation equation without breaking it into two interacting parts with the help of a coupling interacting term Q. Nevertheless, with the found solution may be associated an interacting term Q, and then a number of cosmological interacting models studied in the literature correspond to particular cases of our cosmological model. Specifically those models having constant coupling parametersα,β and interacting terms given by Q =αHρ DM , Q =αHρ DE , Q =αH(ρ DM + ρ DE ) and Q =αHρ DM +βHρ DE , where ρ DM and ρ DE are the energy densities of dark matter and dark energy respectively. The studied set of solutions contains a class of cosmological models presenting a scaling behavior at early and at late times. On the other hand the two-fluid cosmological models considered in this paper also permit a three fluid interpretation which is also discussed. In this reinterpretation, for flat Friedmann-Robertson-Walker cosmologies, the requirement of positivity of energy densities of the dark matter and dark energy components allows the state parameter of dark energy to be in the range −1.37 ω DE < −1/3.

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Probing the coupling between dark components of the universe

Cited by 387 publications

References 111 publications

Models off(R)cosmic acceleration that evade solar system tests

Models off(R)cosmic acceleration that evade solar system tests

Thermodynamical description of the interaction between holographic dark energy and dark matter

On a class of scaling FRW cosmological models

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