Interacting quintessence solution to the coincidence problem

Abstract

We show that a suitable interaction between a scalar field and a matter fluid in a spatially homogeneous and isotropic spacetime can drive the transition from a matter dominated era to an accelerated expansion phase and simultaneously solve the coincidence problem of our present Universe. For this purpose we study the evolution of the energy density ratio of these two components.We demonstrate that a stationary attractor solution is compatible with an accelerated expansion of the Universe. We extend this study to account for dissipation effects due to interactions in the dark matter fluid. Finally, Type Ia supernovae and primordial nucleosynthesis data are used to constrain the parameters of the model.

Beyond the cosmological standard model

“…Similar to natural inflation [107], it has been proposed that the flatness of the quintessnce potential could be protected by the field being a pseudo-Nambu-Goldstone boson [108,109]. Additionally, it has been proposed that dark energy and inflation can both be driven by the same field [110][111][112][113][114][115][116][117][118] Quintessence models have a rich phenomenology; one of the more interesting phenomena is that-by suitably choosing the potential-the energy density in the quintessence field can be made to "track" the energy density in radiation/matter at early times and then grow to dominate the energy budget at late times [119][120][121][122][123][124][125][126]. The canonical example of a potential that produces this behavior is the Ratra-Peebles potential [67] V (φ) = M 4+n φ n , (2.4) where n > 0 is a constant.…”

Quantum induced ω = −1 crossing of the quintessence and phantom models

“…Recently, it has been shown that the ω > −1 to ω < −1 transition always occurs in the quintom models with slowly-varying potentials [9]. Also if one considers one scalar field, but with suitable interaction with background dark matter, again this transition can be occurred [10].…”

Backreaction mechanism in multifluid and extended cosmologies

“…On the other hand, Eq. (2.16) can be obtained by combining the time derivative of (2.10) with (2.13) yieldinġ 19) withR ≡ σ ij R ij and analogouslyπ = σ ij π ij . Terms in expressions (2.16) and (2.19) can be matched using Codazzi-Gauss equations.…”

“…There are strong theoretical arguments to take into account scalar-tensor theories, including the fact that scalar partners of the graviton naturally arise in most attempts to quantise or unify gravity with other interactions and that the coupling between the scalar field and the matter density could provide a mechanism to alleviate the coincidence problem [19]. Scalar-tensor theories are usually formulated in two different frames: the Jordan Frame (JF) and the Einstein Frame (EF).…”