11 research outputs found

    Parametrization of Born-Infeld Type Phantom Dark Energy Model

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    Applying the parametrization of dark energy density, we can construct directly independent-model potentials. In Born-Infeld type phantom dark energy model, we consider four special parametrization equation of state parameter. The evolutive behavior of dark energy density with respect to red-shift zz, potentials with respect to ϕ\phi and zz are shown mathematically. Moreover, we investigate the effect of parameter η\eta upon the evolution of the constructed potential with respect to zz. These results show that the evolutive behavior of constructed Born-Infeld type dark energy model is quite different from those of the other models.Comment: 5 pages, 4 figures, Accepted for publication in Astrophysics & Space Scienc

    The Influence of Free Quintessence on Gravitational Frequency Shift and Deflection of Light with 4D momentum

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    Based on the 4D momentum, the influence of quintessence on the gravitational frequency shift and the deflection of light are examined in modified Schwarzschild space. We find that the frequency of photon depends on the state parameter of quintessence wqw_q: the frequency increases for 1<wq<1/3-1<w_q<-1/3 and decreases for 1/3<wq<0-1/3<w_q<0. Meanwhile, we adopt an integral power number aa (a=3ωq+2a = 3\omega_q + 2) to solve the orbital equation of photon. The photon's potentials become higher with the decrease of ωq\omega_q. The behavior of bending light depends on the state parameter ωq\omega_q sensitively. In particular, for the case of ωq=1\omega_q = -1, there is no influence on the deflection of light by quintessence. Else, according to the H-masers of GP-A redshift experiment and the long-baseline interferometry, the constraints on the quintessence field in Solar system are presented here.Comment: 12 pages, 2 figures, 4 tables. European Physical Journal C in pres

    Unifying phantom inflation with late-time acceleration: scalar phantom-non-phantom transition model and generalized holographic dark energy

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    The unifying approach to early-time and late-time universe based on phantom cosmology is proposed. We consider gravity-scalar system which contains usual potential and scalar coupling function in front of kinetic term. As a result, the possibility of phantom-non-phantom transition appears in such a way that universe could have effectively phantom equation of state at early time as well as at late time. In fact, the oscillating universe may have several phantom and non-phantom phases. As a second model we suggest generalized holographic dark energy where infrared cutoff is identified with combination of FRW parameters: Hubble constant, particle and future horizons, cosmological constant and universe life-time (if finite). Depending on the specific choice of the model the number of interesting effects occur: the possibility to solve the coincidence problem, crossing of phantom divide and unification of early-time inflationary and late-time accelerating phantom universe. The bound for holographic entropy which decreases in phantom era is also discussed.Comment: 13 pages, clarifications/refs added, to match with published versio

    Cosmological Dynamics of Phantom Field

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    We study the general features of the dynamics of the phantom field in the cosmological context. In the case of inverse coshyperbolic potential, we demonstrate that the phantom field can successfully drive the observed current accelerated expansion of the universe with the equation of state parameter wϕ<1w_{\phi} < -1. The de-Sitter universe turns out to be the late time attractor of the model. The main features of the dynamics are independent of the initial conditions and the parameters of the model. The model fits the supernova data very well, allowing for 2.4<wϕ<1-2.4 < w_{\phi} < -1 at 95 % confidence level.Comment: Typos corrected. Some clarifications and references added. To appear in Physical Review

    A Braneworld Dark Energy Model with Induced Gravity and the Gauss-Bonnet Effect

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    We construct a holographic dark energy model with a non-minimally coupled scalar field on the brane where Gauss-Bonnet and Induced Gravity effects are taken into account. This model provides a wide parameter space with several interesting cosmological implications. Especially, the equation of state parameter of the model crosses the phantom divide line and it is possible to realize bouncing solutions in this setup.Comment: 20 pages, 3 eps figures, to appear in IJT
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