Quintom Cosmology: theoretical implications and observations

By Yi Cai, Emmanuel N. Saridakis, M. Setare, J. Xia. 2009

866 citations recorded by the source corpus.

We review the paradigm of quintom cosmology. This scenario is motivated by the observational indications that the equation of state of dark energy across the cosmological constant boundary is mildly favored, although the data are still far from being conclusive. As a theoretical setup we introduce a no-go theorem existing in quintom cosmology, and based on it we discuss the conditions for the equation of state of dark energy realizing the quintom scenario. The simplest quintom model can be achieved by introducing two scalar fields with one being quintessence and the other phantom. Based on the double-field quintom model we perform a detailed analysis of dark energy perturbations and we discuss their effects on current observations. This type of scenarios usually suffer from a manifest problem due to the existence of a ghost degree of freedom, and thus we review various alternative realizations of the quintom paradigm. The developments in particle physics and string theory provide potential clues indicating that a quintom scenario may be obtained from scalar systems with higher derivative terms, as well as from nonscalar systems. Additionally, we construct a quintom realization in the framework of braneworld cosmology, where the cosmic acceleration and the phantom divide crossing result from the combined effects of the field evolution on the brane and the competition between four and five dimensional gravity. Finally, we study the outsets and fates of a universe in quintom cosmology. In a scenario with null energy condition violation one may obtain a bouncing solution at early times and therefore avoid the Big Bang singularity. Furthermore, if this occurs periodically, we obtain a realization of an oscillating universe. Lastly, we comment on several open issues in quintom cosmology and their connection to future investigations.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/a8480c2e47397293602576803b3f97e19dcbf5dd

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Citations in the corpus

f(T,𝒯) gravity and cosmology (2014, background): “The first direction consists in modifying the universe content, by introducing a dark energy sector, starting either with a canonical scalar field, a phantom field, or the combination of both fields in a unified model, and proceeding to more complicated constructions (for reviews see [2, 3] and refe”
New observational constraints on f(R) gravity from cosmic chronometers (2016, background): “Firstly, one can attribute these extra degrees of freedom to new, exotic forms of matter, such as the inflaton field at early times (for reviews see [1, 2]) and/or the dark energy concept at late times (for reviews see [3, 4]).”
Cosmological Models with Linearly Varying Deceleration Parameter (2011, background): “Since the twice contracted Bianchi identity (G ;ν = 0) assures the conservation (1)See [6, 7, 8, 9] and references therein for further reading on DE and see [10] for an extensive review on quintom.”
Dynamical behavior in f (T, TG) cosmology (2014, background): “ng the dark energy concept, with its simpler candidates being a canonical scalar ﬁeld, a phantom ﬁeld or the combination of both ﬁelds in a uniﬁed model dubbed quintom (for reviews on dark energy see [1, 2] and references therein). The second direction that one can follow is to modify the gravitatio”
Exploring bouncing cosmologies with cosmological surveys (2014, methodology): “As a result, the phenomenologies of a nonsingular bouncing cosmology in the very early universe could be associated with the quintom scenario as inspired by the dark energy study of the late time acceleration as reviewed in [26].”
Holographic dark energy (2016, background): “red to satisfy dE Ent = T EntdS Ent; (46) 8In addition to quintessence and phantom, a scalar eld DE may also be a quintom DE, whose EoS can evolve across the cosmological constant boundary [202]. See [203] for a review of quintom DE. 22 where T Ent = 1=(2ˇR h) is the Gibbons-Hawking temperature. Int”