The phantom divide in string gas cosmology

McInnes, Brett

doi:10.1016/j.nuclphysb.2005.04.025

Cited by 102 publications

(70 citation statements)

References 86 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Consequently, one must introduce extra degrees of freedom or introduce the non-minimal couplings or modify the Einstein gravity. In recent years there has been a large amount of research in constructing models with w crossing −1 [80,81,82,84,85,86,87,88,89,90,91,92,93,94,95 …”

Section: The Simplest Quintom Model With Double Fieldsmentioning

confidence: 99%

Quintom cosmology: Theoretical implications and observations

et al. 2010

View full text Add to dashboard Cite

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.

show abstract

Section: The Simplest Quintom Model With Double Fieldsmentioning

confidence: 99%

Quintom cosmology: Theoretical implications and observations

et al. 2010

View full text Add to dashboard Cite

show abstract

“…However, it may be a surprise to see, when λ < 0, the solution will be of a finite lifespan or periodic, instead, depending on how far the parameter A is away from the phantom divide line [28,29,30,31,32], A = −1. To see this fact more transparently, we rewrite the Friedmann equation as…”

Section: Linear Equation Of State Casementioning

confidence: 99%

Friedmann-Lemaitre cosmologies via roulettes and other analytic methods

Chen

Gibbons

Yang

2015

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

In this work a series of methods are developed for understanding the Friedmann equation when it is beyond the reach of the Chebyshev theorem. First it will be demonstrated that every solution of the Friedmann equation admits a representation as a roulette such that information on the latter may be used to obtain that for the former. Next the Friedmann equation is integrated for a quadratic equation of state and for the Randall-Sundrum II universe, leading to a harvest of a rich collection * Email address: chensx@henu.edu.cn † Email address: gwg1@damtp.cam.ac.uk ‡ Email address: yisongyang@nyu.edu 1 of new interesting phenomena. Finally an analytic method is used to isolate the asymptotic behavior of the solutions of the Friedmann equation, when the equation of state is of an extended form which renders the integration impossible, and to establish a universal exponential growth law.Keywords: Astrophysical fluid dynamics, cosmology with extra dimensions, alternatives to inflation, initial conditions and eternal universe, cosmological applications of theories with extra dimensions, string theory and cosmology.

show abstract

“…There has been a steady stream of research on this scenario over recent years (see e.g. [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,36,37,38,39]). …”

Section: Introductionmentioning

confidence: 99%

The cosmology of massless string modes

Patil

Brandenberger

2006

J. Cosmol. Astropart. Phys.

121

View full text Add to dashboard Cite

We consider the spacetime dynamics of a gas of closed strings in the context of General Relativity in a background of arbitrary spatial dimensions. Our motivation is primarily late time String Gas Cosmology, where such a spacetime picture has to emerge after the dilaton has stabilized. We find that after accounting for the thermodynamics of a gas of strings, only string modes which are massless at the self-dual radius are relevant, and that they lead to a dynamics which is qualitatively different from that induced by the modes usually considered in the literature. In the context of an ansatz with three large spatial dimensions and an arbitrary number of small extra dimensions, we obtain isotropic stabilization of these extra dimensions at the self-dual radius. This stabilization occurs for fixed dilaton, and is induced by the special string states we focus on. The three large dimensions undergo a regular Friedmann-Robertson-Walker expansion. We also show that this framework for late-time cosmology is consistent with observational bounds.

show abstract

The phantom divide in string gas cosmology

Cited by 102 publications

References 86 publications

Quintom cosmology: Theoretical implications and observations

Quintom cosmology: Theoretical implications and observations

Friedmann-Lemaitre cosmologies via roulettes and other analytic methods

The cosmology of massless string modes

Contact Info

Product

Resources

About