Nonsingular G2 stiff fluid cosmologies

Fernández–Jambrina, L.; González-Romero, L. M.

doi:10.1063/1.1705715

Cited by 6 publications

(3 citation statements)

References 12 publications

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“…The conditions are fairly easy to implement in terms of a growing function H and a solution to the plane-wave equation with very few restrictions. This is much the same as it happened for stiff perfect fluids [14]. Regular models are pretty general among radiation spacetimes.…”

Section: Discussionsupporting

confidence: 52%

Non-Singular Radiation Cosmological Models

Fernández–Jambrina

González-Romero

2004

Mod. Phys. Lett. A

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Section: Discussionsupporting

confidence: 52%

Non-Singular Radiation Cosmological Models

Fernández–Jambrina

González-Romero

2004

Mod. Phys. Lett. A

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“…The model conforms with standard cosmology (obeys the Einstein equations with Friedmann-Robertson-Walker metric) with this unusual form of matter. While we focus on the Holographic Universe model, a number of authors have considered cosmological aspects of such a stiff fluid in the literature and our conclusions generalize to those models as well [27]- [37], [55]. The microphysical interpretation of this fluid is a dense gas of black holes [23] which is argued by BF to emerge naturally from a quantumgravity regime.…”

Section: Introductionmentioning

confidence: 94%

Perturbations in a holographic universe and in other stiff fluid cosmologies

Battefeld

Easson

2004

Phys. Rev. D

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We examine the generation and evolution of perturbations in a universe dominated by a fluid with stiff equation of state p = ρ. The recently proposed Holographic Universe is an example of such a model. We compute the spectrum of scalar and tensor perturbations, without relying on a microphysical description of the p = ρ fluid. The spectrum is scale invariant deep inside the Hubble horizon. In contrast, infrared perturbations that enter the Hubble horizon during the stiff fluid dominated (holographic) phase yield oscillatory and logarithmic terms in the power spectrum. We show that vector perturbations grow during the stiff fluid dominated epoch and may result in a turbulent and anisotropic Universe at the end of the holographic phase. Therefore, the required period of inflation following the holographic phase cannot be much shorter than that required in standard inflationary models.PACS numbers: 98.80.Cq.

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“…Finally, the integrability conditions of the overdetermined system (24) - (25) are equivalent to the equations (21) - (23), guarantying so the existence of solutions. Now, as we can see from the above system of equations, the stiff fluids equations are easy to integrate due to the fact that, as a consequence of the stiff equation of state p = ρ, the equations for the metric functions U and W decouple from the pressure [29]. In order to solve the system (21) - (25), we first consider solutions of the equation (21) of the general form…”

Section: The Einstein and Matter Evolution Equationsmentioning

confidence: 99%

Two simple families of exact inhomogeneous stiff cosmologies

González¹,

Lora²,

Jaimes³

2008

Braz. J. Phys.

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Two families of exact simple solutions of Einstein field equations for inhomogeneous stiff cosmologies are presented. The method to obtain the solutions is based on the introduction of auxiliary functions in order to cast the Einstein equations in such a way that can be explicitly integrated. Although the equations are mathematically equivalent to the equations obtained when the source of matter is a scalar field, it is worth to mention that the source that we consider is not a scalar field but a perfect fluid with a stiff equation of state. The obtained solutions are expressed in terms of simple functions of the used coordinates and two families of particular solutions are considered. The geometrical and kinematical properties of the solutions are then analyzed and the parameters are restricted in order to have a physically acceptable behavior. The two particular solutions are of the Petrov type I, the first one being regular everywhere whereas the second one presents a big-bang singularity. Now, for a particular value of one of the parameters, the second particular solution is a vacuum solution of the Bianchi I type that reduces to the Kasner solution.

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Nonsingular G2 stiff fluid cosmologies

Cited by 6 publications

References 12 publications

Non-Singular Radiation Cosmological Models

Non-Singular Radiation Cosmological Models

Perturbations in a holographic universe and in other stiff fluid cosmologies

Two simple families of exact inhomogeneous stiff cosmologies

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