Multifield coupled quintessence

Amendola, Luca; Barreiro, Tiago; Nunes, Nelson J.

doi:10.1103/physrevd.90.083508

Cited by 39 publications

(47 citation statements)

References 49 publications

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“…On the other hand, we also found examples such as the strongly coupled model defined in Ref. [16], were f g is incompatible with current observations, ruling out the model. This confirms the conclusion in Ref.…”

Section: Discussioncontrasting

confidence: 78%

“…The background evolution of this system was also studied in Ref. [16] and can be seen in the right hand plot in Figure 3. The initial oscillations in the scalar fields are caused by the initial conditions for the fields, which are set above the minimum of the effective potential and subsequently oscillate around this minimum.…”

Section: Strongly Coupled Matter Dominationmentioning

confidence: 97%

“…[24], we set the baryon density to zero for this model. In previous work, perturbations in this model have been studied using an approximation to the full system of equations [12,16,22,24]. This simplification is valid for modes on subhorizon scales and allows scalar field fluctuations to be written in terms of density perturbations.…”

Section: A Multi-coupled Dark Energy -Mcdementioning

confidence: 99%

“…One example is coupled quintessence. In this model a scalar field, which makes up the dark energy (DE) component of the universe and produces acceleration, is coupled to a pressureless dark matter fluid [10][11][12][13][14][15][16][17][18][19][20][21][22][23]. Recent extensions which have been investigated include Multicoupled Dark Energy (McDE) (see e.g.…”

Section: Introductionmentioning

confidence: 99%

“…Taking this line of investigation, one can model the dark sector of the universe as being made up of N fluids interacting with M scalar fields. This model is known as Multifield or Assisted coupled quintessence [16]. The name derives from the idea that the many fields can act together to generate acceleration, in a similar manner to assisted inflation models of the early universe (see for example [25][26][27]).…”

Section: Introductionmentioning

confidence: 99%

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Linear density perturbations in multifield coupled quintessence

et al. 2017

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We study the behaviour of linear perturbations in multifield coupled quintessence models. Using gauge invariant linear cosmological perturbation theory we provide the full set of governing equations for this class of models, and solve the system numerically. We apply the numerical code to generate growth functions for various examples, and compare these both to the standard ΛCDM model and to current and future observational bounds. Finally, we examine the applicability of the "small scale approximation", often used to calculate growth functions in quintessence models, in light of upcoming experiments such as SKA and Euclid. We find the deviation of the full equation results for large k modes from the approximation exceeds the experimental uncertainty for these future surveys. The numerical code, Pyessence, written in Python will be publicly available.

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Section: Discussioncontrasting

confidence: 78%

Section: Strongly Coupled Matter Dominationmentioning

confidence: 97%

Section: A Multi-coupled Dark Energy -Mcdementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Linear density perturbations in multifield coupled quintessence

et al. 2017

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Remedy of some cosmological tensions via effective phantom-like behavior of interacting vacuum energy

Kumar

2021

Physics of the Dark Universe

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Dynamical systems applied to cosmology: Dark energy and modified gravity

et al. 2018

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The Nobel Prize winning confirmation in 1998 of the accelerated expansion of our Universe put into sharp focus the need of a consistent theoretical model to explain the origin of this acceleration. As a result over the past two decades there has been a huge theoretical and observational effort into improving our understanding of the Universe. The cosmological equations describing the dynamics of a homogeneous and isotropic Universe are systems of ordinary differential equations, and one of the most elegant ways these can be investigated is by casting them into the form of dynamical systems. This allows the use of powerful analytical and numerical methods to gain a quantitative understanding of the cosmological dynamics derived by the models under study. In this review we apply these techniques to cosmology. We begin with a brief introduction to dynamical systems, fixed points, linear stability theory, Lyapunov stability, centre manifold theory and more advanced topics relating to the global structure of the solutions. Using this machinery we then analyse a large number of cosmological models and show how the stability conditions allow them to be tightly constrained and even ruled out on purely theoretical grounds. We are also able to identify those models which deserve further in depth investigation through comparison with observational data. This review is a comprehensive and detailed study of dynamical systems applications to cosmological models focusing on the late-time behaviour of our Universe, and in particular on its accelerated expansion. In self contained sections we present a large number of models ranging from canonical and non-canonical scalar fields, interacting models and non-scalar field models through to modified gravity scenarios. Selected models are discussed in detail and interpreted in the context of late-time cosmology.

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Multifield coupled quintessence

Cited by 39 publications

References 49 publications

Linear density perturbations in multifield coupled quintessence

Linear density perturbations in multifield coupled quintessence

Remedy of some cosmological tensions via effective phantom-like behavior of interacting vacuum energy

Dynamical systems applied to cosmology: Dark energy and modified gravity

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