Essentials of k essence

By C. Armendariz-Picon, V. Mukhanov, Paul J. Steinhardt. 2000

1,542 citations recorded by the source corpus.

We recently introduced the concept of ``k-essence'' as a dynamical solution for explaining naturally why the universe has entered an epoch of accelerated expansion at a late stage of its evolution. The solution avoids fine-tuning of parameters and anthropic arguments. Instead, k-essence is based on the idea of a dynamical attractor solution which causes it to act as a cosmological constant only at the onset of matter domination. Consequently, k-essence overtakes the matter density and induces cosmic acceleration at about the present epoch. In this paper, we present the basic theory of k-essence and dynamical attractors based on evolving scalar fields with nonlinear kinetic energy terms in the action. We present guidelines for constructing concrete examples and show that there are two classes of solutions, one in which cosmic acceleration continues forever and one in which the acceleration has finite duration.

Subfields: Astronomy and Astrophysics, Atmospheric Science

View Paper: https://www.semanticscholar.org/paper/2d60c9995222c6bf1481c27b0a00bf3b5e6dd51e

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Citations in the corpus

Dust of dark energy (2010, methodology): “In the case of time-like derivatives: X > 0, similarly to k-essence [33–35], we can introduce an effective 4-velocity”
The imperfect fluid behind kinetic gravity braiding (2011, background): “37) in the k-essence limit (GX = 0) reduces to the formula sometimes referred to as the k-essence equation of state, E = 2XPX −P [1].”
hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System (2016, background): “[19, 20], kinetic gravity braiding [21–23], covariant galileons [11, 24], disformal and Dirac-Born-Infeld gravity [25–27], Chameleons [28, 29], symmetrons [30, 31], Gauss-Bonnet couplings [32] and models screening the cosmological constant [33, 34].”
Towards a nonsingular bouncing cosmology (2012, background): “The most general form of single scalar field Lagrangian giving rise to second-order field equations in four-dimensional spacetime can be expressed as [51, 52] L = K(φ,X) +G(φ,X) φ+ L4 + L5 , (1) where K and G are functions of a dimensionless scalar field φ and its canonical kinetic term X ≡ ∂µφ∂µφ/2”
Null energy condition and superluminal propagation (2005, background): “Indeed many (most?) of the models that have been considered in recent years in connection to cosmic acceleration [33, 6, 11] feature superluminal excitations around some background.”
Modified Newtonian Dynamics (MOND): Observational Phenomenology and Relativistic Extensions (2011, background): “48 k-essence fields have also recently been reintroduced as possible dark energy fluids, that could also drive inflation [20, 21, 92].”