Crossing the phantom divide

Kunz, M.; Sapone, Domenico

doi:10.1103/physrevd.74.123503

Cited by 117 publications

(162 citation statements)

References 23 publications

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“…Dynamical dark energy will have large-scale fluctuations [20]. Furthermore, it may also have non-negligible anisotropic stress and is thus able to mimic modifications in gravity [21]. But, for models with large sound speed and negligible anisotropic stress, such as quintessence, these are negligible at sub-horizon scales and Eq.…”

Section: Where ∆Cmentioning

confidence: 99%

Probing Gravity at Cosmological Scales by Measurements which Test the Relationship between Gravitational Lensing and Matter Overdensity

et al. 2007

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The standard cosmological model is based on general relativity and includes dark matter and dark energy. An important prediction of this model is a fixed relationship between the gravitational potentials responsible for gravitational lensing and the matter overdensity. Alternative theories of gravity often make different predictions for this relationship. We propose a set of measurements which can test the lensing/matter relationship, thereby distinguishing between dark energy/matter models and models in which gravity differs from general relativity. Planned optical, infrared and radio galaxy and lensing surveys will be able to measure EG, an observational quantity whose expectation value is equal to the ratio of the Laplacian of the Newtonian potentials to the peculiar velocity divergence, to percent accuracy. We show that this will easily separate alternatives such as ΛCDM, DGP, TeVeS and f (R) gravity.

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Section: Where ∆Cmentioning

confidence: 99%

Probing Gravity at Cosmological Scales by Measurements which Test the Relationship between Gravitational Lensing and Matter Overdensity

et al. 2007

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“…where δ = δρ/ρ is the density contrast, V = ik j T j 0 /ρ is the scalar velocity perturbation (see also [13]) and the prime means the derivative with respect to the scale factor a. In this paper we will look only at fluids with vanishing anisotropic stress, σ = 0, so that there is a single gravitational potential,…”

Section: First Order Perturbations In Matter and Dark Energymentioning

confidence: 99%

Fingerprinting dark energy

2009

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Dark energy perturbations are normally either neglected or else included in a purely numerical way, obscuring their dependence on underlying parameters like the equation of state or the sound speed. However, while many different explanations for the dark energy can have the same equation of state, they usually differ in their perturbations so that these provide a fingerprint for distinguishing between different models with the same equation of state. In this paper we derive simple yet accurate approximations that are able to characterize a specific class of models (encompassing most scalarfield models) which is often generically called "dark energy". We then use the approximate solutions to look at the impact of the dark energy perturbations on the dark matter power spectrum and on the integrated Sachs-Wolfe effect in the cosmic microwave background radiation.PACS numbers: 98.80.-k; 95.36.+x

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“…(38) and Eq. (39), and assuming the total equation of state w is a constant, we find the energy density is…”

Section: Cosmological Constant and Phantom From Quintessence A mentioning

confidence: 99%

“…The rest frame sound speed squaredĉ 2 s of the scalar is related to the pressure perturbation in the Newtonian gauge through [37,38] …”

Section: B Speed Of Soundmentioning

confidence: 99%

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Cosmological models with Lagrange multiplier field

2011

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We first consider the Einstein-aether theory with a gravitational coupling and a Lagrange multiplier field, and then consider the non-minimally coupled quintessence field theory with Lagrange multiplier field. We study the influence of the Lagrange multiplier field on these models. We show that the energy density evolution of the Einstein-aether field and the quintessence field are significantly modified. The energy density of the Einstein-aether is nearly a constant during the entire history of the Universe. The energy density of the quintessence field can also be kept nearly constant in the matter dominated Universe, or even exhibit a phantom-like behavior for some models. This suggests a possible dynamical origin of the cosmological constant or dark energy. Further more, for the canonical quintessence in the absence of gravitational coupling, we find that the quintessence scalar field can play the role of cold dark matter with the introduction of a Lagrange multiplier field. We conclude that the Lagrange multiplier field could play a very interesting and important role in the construction of cosmological models.

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Crossing the phantom divide

Cited by 117 publications

References 23 publications

Probing Gravity at Cosmological Scales by Measurements which Test the Relationship between Gravitational Lensing and Matter Overdensity

Probing Gravity at Cosmological Scales by Measurements which Test the Relationship between Gravitational Lensing and Matter Overdensity

Fingerprinting dark energy

Cosmological models with Lagrange multiplier field

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