Phase-space analysis of interacting phantom cosmology

We construct gravitational modifications that go beyond Horndeski, namely theories with extended nonminimal derivative couplings, in which the coefficient functions depend not only on the scalar field but also on its kinetic energy. Such theories prove to be ghost-free in a cosmological background. We investigate the early-time cosmology and show that a de Sitter inflationary phase can be realized as a pure result of the novel gravitational couplings. Additionally, we study the latetime evolution, where we obtain an effective dark energy sector which arises from the scalar field and its extended couplings to gravity. We extract various cosmological observables and analyse their behavior at small redshifts for three choices of potentials, namely, for the exponential, the powerlaw, and the Higgs potential. We show that the Universe passes from deceleration to acceleration in the recent cosmological past, while the effective dark-energy equation-of-state parameter tends to the cosmological-constant value at present. Finally, the effective dark energy can be phantom-like, although the scalar field is canonical, which is an advantage of the model.PACS numbers: 04.50. Kd, 95.36.+x

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“…Additionally, concerning the scalar potential we will consider three well-known cases, namely the exponential potential [69][70][71][72][73]:…”

Section: Late-time Cosmologymentioning

confidence: 99%

Cosmological models in modified gravity theories with extended nonminimal derivative couplings

2017

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“…To analyse the dynamical system of the interacting polytropic gases considered in this section, one follows to existing scientific literature (see for instance [83]). There is a huge number of articles presenting the phase space analysis of different cosmological models [83][84][85][86][87][88][89][90] (to mention a few).…”

Section: Alternative Look At the Problemmentioning

confidence: 99%

On the Phenomenology of an Accelerated Large-Scale Universe

Khurshudyan

2016

Symmetry

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Abstract:In this review paper, several new results towards the explanation of the accelerated expansion of the large-scale universe is discussed. On the other hand, inflation is the early-time accelerated era and the universe is symmetric in the sense of accelerated expansion. The accelerated expansion of is one of the long standing problems in modern cosmology, and physics in general. There are several well defined approaches to solve this problem. One of them is an assumption concerning the existence of dark energy in recent universe. It is believed that dark energy is responsible for antigravity, while dark matter has gravitational nature and is responsible, in general, for structure formation. A different approach is an appropriate modification of general relativity including, for instance, f (R) and f (T) theories of gravity. On the other hand, attempts to build theories of quantum gravity and assumptions about existence of extra dimensions, possible variability of the gravitational constant and the speed of the light (among others), provide interesting modifications of general relativity applicable to problems of modern cosmology, too. In particular, here two groups of cosmological models are discussed. In the first group the problem of the accelerated expansion of large-scale universe is discussed involving a new idea, named the varying ghost dark energy. On the other hand, the second group contains cosmological models addressed to the same problem involving either new parameterizations of the equation of state parameter of dark energy (like varying polytropic gas), or nonlinear interactions between dark energy and dark matter. Moreover, for cosmological models involving varying ghost dark energy, massless particle creation in appropriate radiation dominated universe (when the background dynamics is due to general relativity) is demonstrated as well. Exploring the nature of the accelerated expansion of the large-scale universe involving generalized holographic dark energy model with a specific Nojiri-Odintsov cut-off is presented to finalize the paper.

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“…(6)- (8) as an autonomous system of equations, but can also be generalized in different contexts such as nonminimally coupled scalar fields [20][21][22][23], tachyons [24], Galileons [25], phantom and quintom cosmology [26,27], k-essence [28,29], modified gravity [30], three-form cosmology [31,32] and dark energy models coupled to dark matter [33][34][35].…”

Section: The Canonical Scalar Fieldmentioning

confidence: 99%

Dynamics of cosmological scalar fields

Tamanini

2014

Phys. Rev. D

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The background dynamical evolution of a universe filled with matter and a cosmological scalar field is analyzed employing dynamical system techniques. After the phenomenology of a canonical scalar field with exponential potential is revised, square and square root kinetic corrections to the scalar field canonical Lagrangian are considered and the resulting dynamics at cosmological distances is obtained and studied. These noncanonical cosmological models imply new interesting phenomenology including early time matter dominated solutions, cosmological scaling solutions and late time phantom dominated solutions with dynamical crossing of the phantom barrier. Stability and viability issues for these scalar fields are presented and discussed.

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Phase-space analysis of interacting phantom cosmology

Cited by 151 publications

References 102 publications

Cosmological models in modified gravity theories with extended nonminimal derivative couplings

Cosmological models in modified gravity theories with extended nonminimal derivative couplings

On the Phenomenology of an Accelerated Large-Scale Universe

Dynamics of cosmological scalar fields

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