8/25/2006 · We demonstrate that if k-essence can solve the coincidence problem and play the role of dark energy in the Universe, the fluctuations of the field have to propagate superluminally at some stage. We argue that this implies that successful k-essence models violate causality.
Early dark energy (EDE) that becomes subdominant around the epoch of matter-radiation equality can be used to ease the Hubble tension. However, there is a theoretical problem that why the energy …
We demonstrate that if k-essence can solve the coincidence problem and play the role of dark energy in the Universe, the fluctuations of the field have to propagate superluminally at some stage.
5/15/2009 · The Lagrangian contains a potential for the scalar field as well as a noncanonical kinetic term, and is of the form F(X)V({phi}) which has been widely used as a k-essence Lagrangian. After the period of inflation is over the model can be approximated as purely kinetic k essence, generating dark matter and dark energy at late times.
Dark Matter to Dark Energy Transition in k-ESSENCE Cosmologies. Modern Physics Letters A, 2005. Ruth Lazkoz. PDF. Download Free PDF. Free PDF. Download PDF. PDF. PDF. Download PDF Package. PDF. … Phase-space analysis of a class of k-essence cosmology. By Xinbo Gao. DBI models for the unification of dark matter and dark energy .
Dark energy – Wikipedia, Dark energy – Wikipedia, Dark energy – Wikipedia, Dark energy – Wikipedia, 10/18/2012 · Abstract: We study an early dark energy (EDE) model as a K-essence scalar field in the framework of FLRW universe using an effective parametrization of the state equation as a function of the redshift $z$ with the tracker condition during radiation domination, but also demanding an accelerated expansion of the universe at late times emulating cosmological constant. We found all the dynamical variables of the EDE .
12/22/2005 · Quintessence and k-essence have been proposed as candidates for the dark energy component of the universe that would be responsible of the currently observed accelerated expansion. In this Letter we investigate the degree of resemblance between those two theoretical setups, and find that every quintessence model can be viewed as a k-essence model generated by a kinetic linear function.
The violation of NEC by the dynamical Dark Energy (DE) is not excluded and even slightly preferred by observations Moreover, the violation of NEC plays a crucial role in the pre-Big-Bang scenarios. We have shown that in the framework of general k-essence the dynamical violation of NEC is.
An holographic k-essence model of dark energy was proposed in [14]. The geometrical diagnostic for purely kinetic k-essence dark energy was discussed in [15]. The equivalence of a barotropic perfect fluid with a k-essence scalar field was considered in [16, 17].
9/14/2002 · Some special cases of quintessence are phantom energy , in which the energy density of quintessence actually increases with time, and k-essence (short for kinetic quintessence) which has a non-standard form of kinetic energy such as a negative kinetic energy . They can have unusual properties: phantom energy , for example, can cause a Big Rip.
Brian Schmidt, Saul Perlmutter, Max Tegmark, Nicholas B. Suntzeff, Robert Kirshner
