Phantom cosmologies

Dąbrowski, Mariusz P.; Stachowiak, Tomasz; Szydłowski, Marek

doi:10.1103/physrevd.68.103519

Cited by 289 publications

(157 citation statements)

References 40 publications

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“…As η 0 decreases to get closer to the value −1, the regularity of the geodesic improves in the sense that one has to go to derivatives of higher order to find singular behavior. This limit model has been named superphantom [15] in the case of flat power-law cosmologies with w = −5/3. For η 0 greater or equal than −1 these geodesics do not even reach the event at t 0 .…”

Section: Lightlike Geodesicsmentioning

confidence: 99%

Classification of cosmological milestones

2006

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In this paper causal geodesic completeness of FLRW cosmological models is analysed in terms of generalised power expansions of the scale factor in coordinate time. The strength of the found singularities is discussed following the usual definitions due to Tipler and Królak. It is shown that while classical cosmological models are both timelike and lightlike geodesically incomplete, certain observationally alllowed models which have been proposed recently are lightlike geodesically complete.

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Section: Lightlike Geodesicsmentioning

confidence: 99%

Classification of cosmological milestones

2006

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“…At the end of the phantom dark energy era, at a finite time t s , the scale factor and the Hubble rate of the model strongly diverge and this indicates that a Big Rip or some sort of Rip singularity [48][49][50][51][52][53][54][55] is reached. However, a few seconds before this Rip singularity, the effective energy density and the effective pressure of the model become complex and thus this singularity is unphysical.…”

Section: Introductionmentioning

confidence: 99%

Deformed matter bounce with dark energy epoch

Odintsov

Oikonomou

2016

Phys. Rev. D

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We extend the Loop Quantum Cosmology matter bounce scenario in order to include a dark energy era, which ends abruptly at a Rip singularity where the scale factor and the Hubble rate diverge. In the "deformed matter bounce scenario", the Universe is contracting from an initial non-causal matter dominated era until it reaches a minimal radius. After that it expands in a decelerating way, until at late times, where it expands in an accelerating way, thus the model is described by a dark energy era that follows the matter dominated era. Depending on the choice of the free parameters of the model, the dark energy era is quintessential like which follows the matter domination era, and eventually it crosses the phantom divide line and becomes phantom. At the end of the dark energy era, a Rip singularity exists, where the scale factor and Hubble rate diverge, however the physical system cannot reach the singularity, since the effective energy density and pressure become complex. This indicates two things, firstly that the ordinary Loop Quantum Cosmology matter bounce evolution stops, thus ending the infinite repetition of the ordinary matter bounce scenario. Secondly, the fact that both the pressure and the density become complex indicates probably that the description of the cosmic evolution within the theoretical context of Loop Quantum Cosmology, ceases to describe the physics of the system and possibly a more fundamental theory of quantum gravity is needed near the would be Rip singularity. We describe the qualitative features of the model and we also investigate how this cosmology could be realized by a viscous fluid in the context of Loop Quantum Cosmology. In addition to this, we show how this deformed model can be realized by a canonical scalar field filled Universe, in the context of Loop Quantum Cosmology. Finally, we demonstrate how the model can be generated by a vacuum F (R) gravity.

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“…In the regime ρ > ρ crit /2, a massive scalar field behaves as a phantom field in the standard cosmology, and a phantom field mimics dynamics of an ordinary scalar field. We would then investigate various symmetries between the expanding branch, the contracting branch and the dynamics of a phantom scalar field and show that as in the standard Friedmann cosmology [22,23] and the RandallSundrum scenario [23], they have a dual relationship with each other in the effective theory of LQC.…”

Section: Introductionmentioning

confidence: 99%

Loop cosmological dynamics and dualities with Randall-Sundrum braneworlds

2006

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The discrete quantum geometric effects play an important role in dynamical evolution in the loop quantum cosmology. These effects which are significant at the high energies lead to the quadratic energy density modifications to the Friedmann equation, as in the Randall-Sundrum braneworld scenarios but with a negative sign. We investigate the scalar field dynamics in this scenario and show the existence of a phase of super-inflation independent of the inverse scale factor modifications as found earlier. In this regime the scalar field mimics the dynamics of a phantom field and vice versa. We also find various symmetries between the expanding phase, the contracting phase and the phantom phase in the loop quantum cosmology. We then construct the scaling solutions in the loop quantum cosmology and show their dual relationship with those of the Randall-Sundrum cosmology.

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Phantom cosmologies

Cited by 289 publications

References 40 publications

Classification of cosmological milestones

Classification of cosmological milestones

Deformed matter bounce with dark energy epoch

Loop cosmological dynamics and dualities with Randall-Sundrum braneworlds

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