Large scale structure and the generalized Chaplygin gas as dark energy

The generalized Chaplygin gas is characterized by the equation of state p = −A/ρ α , with α > −1 and w > −1. We generalize this model to allow for the cases where α < −1 or w < −1. This generalization leads to three new versions of the generalized Chaplygin gas: an early phantom model in which w ≪ −1 at early times and asymptotically approaches w = −1 at late times, a late phantom model with w ≈ −1 at early times and w → −∞ at late times, and a transient model with w ≈ −1 at early times and w → 0 at late times. We consider these three cases as models for dark energy alone and examine constraints from type Ia supernovae and from the subhorizon growth of density perturbations. The transient Chaplygin gas model provides a possible mechanism to allow for a currently accelerating universe without a future horizon, while some of the early phantom models produce w < −1 without either past or future singularities.

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“…[7], while the case of a smooth, unclustered GCG dark energy component was examined in Ref. [43]. We take the latter approach here.…”

Section: Growth Of Linear Density Perturbationsmentioning

confidence: 99%

Generalizing the generalized Chaplygin gas

Sen¹,

Scherrer

2005

Phys. Rev. D

106

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“…(The constant α regulates the transition time in the equation of state.) WMAP, supernovae and large scale sructure data have all been used to test Chaplygin gas models; see [27,65,78,9,14,22,115,128,56,25]. …”

Section: Chaplygin Gasmentioning

confidence: 99%

5 Dark Matter and Dark Energy

Sahni¹

2004

The Physics of the Early Universe

485

287

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Abstract. I briefly review our current understanding of dark matter and dark energy. The first part of this paper focusses on issues pertaining to dark matter including observational evidence for its existence, current constraints and the 'abundance of substructure' and 'cuspy core' issues which arise in CDM. I also briefly describe MOND. The second part of this review focusses on dark energy. In this part I discuss the significance of the cosmological constant problem which leads to a predicted value of the cosmological constant which is almost 10 123 times larger than the observed value Λ/8πG ≃ 10 −47 GeV 4 . Setting Λ to this small value ensures that the acceleration of the universe is a fairly recent phenomenon giving rise to the 'cosmic coincidence' conundrum according to which we live during a special epoch when the density in matter and Λ are almost equal. Anthropic arguments are briefly discussed but more emphasis is placed upon dynamical dark energy models in which the equation of state is time dependent. These include Quintessence, Braneworld models, Chaplygin gas and Phantom energy. Model independent methods to determine the cosmic equation of state and the Statefinder diagnostic are also discussed. The Statefinder has the attractive property ... a /aH 3 = 1 for LCDM, which is helpful for differentiating between LCDM and rival dark energy models. The review ends with a brief discussion of the fate of the universe in dark energy models.

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“…The case, where the Chaplygin gas is mixed with CDM, has been considered in a number of papers [23,24,25,26,27,28,29,30]. Here, the Chaplygin gas simply plays the role of DE.…”

Section: Introductionmentioning

confidence: 99%

Cosmological tachyon condensation

2009

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We consider the prospects for dark matter/energy unification in k-essence type cosmologies. General mappings are established between the k-essence scalar field, the hydrodynamic and braneworld descriptions. We develop an extension of the general relativistic dust model that incorporates the effects of both pressure and the associated acoustic horizon. Applying this to a tachyon model, we show that this inhomogeneous "variable Chaplygin gas" does evolve into a mixed system containing cold dark matter like gravitational condensate in significant quantities. Our methods can be applied to any dark energy model, as well as to mixtures of dark energy and traditional dark matter.

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Large scale structure and the generalized Chaplygin gas as dark energy

Cited by 86 publications

References 40 publications

Generalizing the generalized Chaplygin gas

Generalizing the generalized Chaplygin gas

5 Dark Matter and Dark Energy

Cosmological tachyon condensation

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