Tachyon reconstruction of ghost dark energy

Sheykhi, Ahmad; Movahed, M. Sadegh; Ebrahimi, Esmaeil

doi:10.1007/s10509-012-0977-x

Cited by 53 publications

(33 citation statements)

References 57 publications

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“…A thermodynamical description of GDE is discussed in [37]. Tachyon and quintessence reconstruction of GDE model were studied in [38] and [39] respectively. The study has also been extended to Brans-Dicke theory [40].…”

Section: Introductionmentioning

confidence: 99%

Instability of QCD Ghost Dark Energy Model

Ebrahimi

Sheykhi

2011

Int. J. Mod. Phys. D

101

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We investigate the instability of the ghost dark energy model against perturbations in different cases. To this goal we use the squared sound speed v 2 s whose sign determines the stability of the model. When v 2 s < 0 the model is unstable against perturbation. At first we discuss the noninteracting ghost dark energy model in a flat FRW universe and find out that such a model is unstable due to the negativity of the v 2 s in all epoches. The interacting ghost dark energy model in both flat and non-flat universe are studied in the next parts and in both cases we find that the squared sound speed of ghost dark energy is always negative. This implies that the perfect fluid for ghost dark energy is classically unstable against perturbations. In both flat and non flat cases we find that the instability of the model increases with increasing the value of the interacting coupling parameter.

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Section: Introductionmentioning

confidence: 99%

Instability of QCD Ghost Dark Energy Model

Ebrahimi

Sheykhi

2011

Int. J. Mod. Phys. D

101

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“…Cosmological observations such as type Ia supernova [1,2], WMAP [3,4] and Large Scale Structure (LSS) [5][6][7] indicate that our Universe is now experiencing a phase of accelerated expansion [8]. This accelerated phase of the Universe expansion is describable by a mysterious source of energy (DE) whose energy density ρ DE and pressure P DE filling about 0.73 percent of the Universe, while ρ DE + 3P DE < 0 meaning that its equation of state (EoS) parameter, ω DE = P DE /ρ DE , must satisfy the condition ω DE < −1/3 [9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25]. An interesting attempt to find a physical origin for DE is called the holographic dark energy (HDE) making a relation between the system entropy and the UV cutoff (or equally the energy density of quantum fields in vacuum) [26].…”

Section: Introductionmentioning

confidence: 99%

Effects of anisotropy on the sign-changeable interacting Tsallis holographic dark energy

et al. 2019

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A spatially homogeneous and anisotropic Bianchi type I universe is considered while it is filled by pressureless dark matter (DM) and Tsallis holographic dark energy (DE) interacting with each other throughout a sign-changeable mutual interaction. Various infra-red (IR) cutoffs are studied, and it has been obtained that while the current universe can classically be stable for some cases, all models display classical instability by themselves at the future (z → −1). Moreover, we find out that some models can cross the phantom line. In order to have a more comprehensive study, the statefinder diagnostic and the ωD − ω ′ D plane are also investigated showing that the model parameters significantly affect the evolution trajectories in the r − s and ωD − ω ′ D planes. *

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“…This vacuun energy density in the QCD ghost dark energy model is proportional to the Hubble parameter H and the proportional coefficient is of the order Λ 3 QCD , where Λ QCD is the mass scale of QCD. From this proposal, many studies in different contexts have been carried out in recent years [14,15,16,17,18,19,20,21,22,23]. The generalization of the ghost dark energy model was carried out in [24], where the studied energy density is of the form ρ Λ = αH + βH 2 .…”

Section: Introductionmentioning

confidence: 99%

Ghost Dark Energy Model with Non-linear Interaction

Revistas¹,

García²

2018

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In this paper we study a dark energy model taking into account a non-linear interaction between the dark energy and dark matter components. The non-linear interaction term, used in this work, is proportional to the square of dark energy density. Considering a FRW type flat universe, we obtain an analytical expression for the Hubble parameter H and from this quantity, the deceleration parameter q and the equation of state parameter w Λ are analyzed. We found that, in this scenario, the accelerated expansion regime of the universe in late times is possible. However, using suitable values for the coupling constant, the square of the speed of sound remains negative, therefore, the model is unstable under small perturbations.Keywords: Dark Energy; Cosmology. IntroductionThe accelerated expansion of the universe was discovered in 1998 from the analysis of astrophysical information obtained from the supernovae type Ia (SNIa) (basically, from measurement of luminosity distances) [1], as well as from the anisotropies observed in the cosmic microwave background (CMB) radiation [2], and the study of the large scale structure (LSS) of the universe [3]. This accelerated expansion is consistent with the idea that the universe has an unknown form of energy density with negative pressure, so called dark energy (DE). The amount of DE in the universe is about 70% and the remaining 30% correspond to matter and radiation densities. A huge amount of DE models have been proposed in the literature [4,5,6], but until now, there is not a satisfactory explanation of this phenomenon. In the ΛCDM model, the role of DE is played by the cosmological constant Λ (vacuum energy), but this model has two main problems: the fine tuning problem and the coincidence problem [7].Recently, a different proposal has attracted considerable attention, a model which has its roots on the Veneziano ghost of QCD [8,9,10,11] and is known as QCD ghost dark energy [12]. The key ingredient of this new model is that

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Tachyon reconstruction of ghost dark energy

Cited by 53 publications

References 57 publications

Instability of QCD Ghost Dark Energy Model

Instability of QCD Ghost Dark Energy Model

Effects of anisotropy on the sign-changeable interacting Tsallis holographic dark energy

Ghost Dark Energy Model with Non-linear Interaction

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