منابع مشابه
Extended Quintessence and its Late-time Domination
Various astronomical observations point towards the evidence for dark energy. One of the most mysterious problem is the coincidence problem: why dark energy becomes dominant only recently. We present a scenario based on extended quintessence models to explain the late-time domination of dark energy without severe fine-tuning of initial conditions and model parameters. PACS numbers: 98.80.Es; 98...
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We study a class of extended quintessence cosmologies where the scalar field playing the role of the dark energy is exponentially coupled to the Ricci scalar. We find that the dynamics induced by the effective gravitational potential in the Klein-Gordon equation dominates the motion of the field in the early universe. The resulting “R−boost” trajectory is characterized by a kinetic dark energy ...
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Good tracking requires that the quintessence energy fraction slowly increase while the roll λ ≡ −d lnV/κdφ slowly decreases, but is not yet truly slow-rolling. The supernova bound on the present quintessence equation of state requires either (1) a cosmological constant or other finetuned ”crawling quintessence” or (2) ”roll-over quintessence” that tracked until recently, but now became slow rol...
متن کاملSub-horizon Perturbation Behavior in Extended Quintessence
In the general context of scalar-tensor theories, we consider a model in which a scalar field coupled to the Ricci scalar in the gravitational sector of the Lagrangian, is also playing the role of an “Extended Quintessence” field, dominating the energy content of the Universe at the present time. In this framework, we study the linear evolution of the perturbations in the Quintessence energy de...
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We obtain constraints on quintessence models from magnitude-redshift measurements of 172 type Ia Supernovae. The considered quintessence models are ordinary quintessence, with Ratra-Peebles and SUGRA potentials, and extended quintessence with a Ratra-Peebles potential. We compute confidence regions in the Ωm0 −α plane and find that for SUGRA potentials it is not possible to obtain useful constr...
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ژورنال
عنوان ژورنال: Physical Review D
سال: 2000
ISSN: 0556-2821,1089-4918
DOI: 10.1103/physrevd.62.123510