6,384 research outputs found
Dynamics of interacting quintessence
In this paper, we investigate coupled quintessence with scaling potential
assuming specific forms of the coupling as namely, ,
and , and
present phase space analysis for three different interacting models. We focus
on the attractor solutions that can give rise to late time acceleration with
of order unity in order to alleviate the coincidence
problem.Comment: 11 pages, 3 figures, matches with the published versio
Dynamics of Interacting Quintessence Models: Observational Constraints
Interacting quintessence models have been proposed to explain or, at least,
alleviate the coincidence problem of late cosmic acceleration. In this paper we
are concerned with two aspects of these kind of models: (i) the dynamical
evolution of the model of Chimento et al. [L.P. Chimento, A.S. Jakubi, D.
Pavon, and W. Zimdahl, Phys. Rev. D 67, 083513 (2003).], i.e., whether its
cosmological evolution gives rise to a right sequence of radiation, dark matter
and dark energy dominated eras, and (ii) whether the dark matter dark energy
ratio asymptotically evolves towards a non-zero constant. After showing that
the model correctly reproduces these eras, we correlate three data sets that
constrain the interaction at three redshift epochs: , ,
and . We discuss the model selection and argue that even if the model
under consideration fulfills both requirements, it is heavily constrained by
observation. The prospects that the coincidence problem can be explained by the
coupling of dark matter to dark energy are not clearly favored by the data.Comment: 16 pages, 7 figures and 3 tables. Modifications introduced to match
published versio
A Two-Field Quintessence Model
We study the dynamics of a quintessence model based on two interacting scalar
fields. The model can account for the (recent) accelerated expansion of the
Universe suggested by astronomical observations. Acceleration can be permanent
or temporary and, for both scenarios, it is possible to obtain suitable values
for the cosmological parameters while satisfying the nucleosynthesis constraint
on the quintessence energy density. We argue that the model dynamics can be
made consistent with a stable zero-energy relaxing supersymmetric vacuum.Comment: 4 pages, 3 eps figures, to be published in Phys. Rev.
Dynamics of interacting phantom and quintessence dark energies
We present models, in which phantom energy interacts with two different types
of dark energies including variable modified Chaplygin gas (VMCG) and new
modified Chaplygin gas (NMCG). We then construct potentials for these cases. It
has been shown that the potential of the phantom field decreases from a higher
value with the evolution of the Universe.Comment: 7 pages, 6 figures, accepted for publication in Astrophysics and
Space Scienc
A late time acceleration of the universe with two scalar fields : many possibilities
In the present work, an attempt has been made to explain the recent cosmic
acceleration with two mutually interacting scalar fields, one being the
Brans-Dicke scalar field and the other a quintessence scalar field. Conditions
have been derived for which the quintessence scalar field has an early
oscillation and it grows during a later time to govern the dynamics of the
universe.Comment: 8 pages, no figures. Accepted for publication in Mod. Phys. Lett.
Supersymmetric Majorana Quantum Cosmologies
The Einstein equations for an isotropic and homogeneous
Friedmann--Robertson--Walker Universe in the presence of a quintessence scalar
field are shown to be described in a unified way, formally identical to the
dynamics of a relativistic particle moving on a two--dimensional spacetime. The
correct Lagrangian for the system is presented and used to construct a spinor
quantum cosmology theory using Breit's prescription. The theory is
supersymmetric when written in Majorana representation. The spinor components
interact through a potential that unifies spacetime curvature and quintessence.
An exact supersymmetric solution for case is exhibited. This quantum
cosmology model may be interpreted as a theory of interacting universes.Comment: 5 page
Cosmological Evolution of Interacting New Holographic Dark Energy in Non-flat Universe
We consider the interacting holographic dark energy with new infrared cutoff
(involving Hubble parameter and its derivative) in non-flat universe. In this
context, we obtain the equation of state parameter which evolutes the universe
from vacuum dark energy region towards quintessence region for particular
values of constant parameters. It is found that this model always remains
unstable against small perturbations. Further, we establish the correspondence
of this model having quintessential behavior with quintessence, tachyon,
K-essence and dilaton scalar field models. The dynamics of scalar fields and
potentials indicate accelerated expansion of the universe which is consistent
with the current observations. Finally, we discuss the validity of the
generalized second law of thermodynamics in this scenario.Comment: 21 pages, 13 figure
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