3,139 research outputs found
Electrodynamics of a Cosmic Dark Fluid
Cosmic Dark Fluid is considered as a non-stationary medium, in which
electromagnetic waves propagate, and magneto-electric field structures emerge
and evolve. A medium - type representation of the Dark Fluid allows us to
involve into analysis the concepts and mathematical formalism elaborated in the
framework of classical covariant electrodynamics of continua, and to
distinguish dark analogs of well-known medium-effects, such as optical
activity, pyro-electricity, piezo-magnetism, electro- and magneto-striction and
dynamo-optical activity. The Dark Fluid is assumed to be formed by a duet of a
Dark Matter (a pseudoscalar axionic constituent) and Dark Energy (a scalar
element); respectively, we distinguish electrodynamic effects induced by these
two constituents of the Dark Fluid. The review contains discussions of ten
models, which describe electrodynamic effects induced by Dark Matter and/or
Dark Energy. The models are accompanied by examples of exact solutions to the
master equations, correspondingly extended; applications are considered for
cosmology and space-times with spherical and pp-wave symmetries. In these
applications we focused the attention on three main electromagnetic phenomena
induced by the Dark Fluid: first, emergence of Longitudinal Magneto-Electric
Clusters; second, generation of anomalous electromagnetic responses; third,
formation of Dark Epochs in the Universe history.Comment: 39 pages, 0 figures, replaced by the version published in MDPI
Journal "Symmetry" (Special Issue: Symmetry: Feature Papers 2016); typos
correcte
Electrodynamic phenomena induced by a dark fluid: Analogs of pyromagnetic, piezoelectric, and striction effects
We establish a new model of coupling between a cosmic dark fluid and
electrodynamic systems, based on an analogy with effects of electric and
magnetic striction, piezo-electricity and piezo-magnetism, pyro-electricity and
pyro-magnetism, which appear in classical electrodynamics of continuous media.
Extended master equations for electromagnetic and gravitational fields are
derived using Lagrange formalism. A cosmological application of the model is
considered, and it is shown that a striction-type interaction between the dark
energy (the main constituent of the dark fluid) and electrodynamic system
provides the universe history to include the so-called unlighted epochs, during
which electromagnetic waves can not propagate and thus can not scan the
universe interior.Comment: 14 pages, 1 Figure, accepted for publication in Phys.Rev.
Electrodynamics of a Cosmic Dark Fluid
© 2016 by the authors.Cosmic Dark Fluid is considered as a non-stationary medium, in which electromagnetic waves propagate, and magneto-electric field structures emerge and evolve. A medium-type representation of the Dark Fluid allows us to involve in its analysis the concepts and mathematical formalism elaborated in the framework of classical covariant electrodynamics of continua, and to distinguish dark analogs of well-known medium-effects, such as optical activity, pyro-electricity, piezo-magnetism, electro- and magneto-striction and dynamo-optical activity. The Dark Fluid is assumed to be formed by a duet of a Dark Matter (a pseudoscalar axionic constituent) and Dark Energy (a scalar element); respectively, we distinguish electrodynamic effects induced by these two constituents of the Dark Fluid. The review contains discussions of 10 models, which describe electrodynamic effects induced by Dark Matter and/or Dark Energy. The models are accompanied by examples of exact solutions to the master equations, correspondingly extended; applications are considered for cosmology and space-times with spherical and pp-wave symmetries. In these applications we focused the attention on three main electromagnetic phenomena induced by the Dark Fluid: first, emergence of Longitudinal Magneto-Electric Clusters; second, generation of anomalous electromagnetic responses; third, formation of Dark Epochs in the Universe history
Correspondence between Electro-Magnetic Field and other Dark Energies in Non-linear Electrodynamics
In this work, we have considered the flat FRW model of the universe filled
with electro-magnetic field. First, the Maxwell's electro-magnetic field in
linear form has been discussed and after that the modified Lagrangian in
non-linear form for accelerated universe has been considered. The corresponding
energy density and pressure for non-linear electro-magnetic field have been
calculated. We have found the condition such that the electro-magnetic field
generates dark energy. The correspondence between the electro-magnetic field
and the other dark energy candidates namely tachyonic field, DBI-essence,
Chaplygin gas, hessence dark energy, k-essenece and dilaton dark energy have
been investigated. We have also reconstructed the potential functions and the
scalar fields in this scenario.Comment: 11 pages, 7 figure
Stability of Accelerated Expansion in Nonlinear Electrodynamics
This paper is devoted to study the phase space analysis of isotropic and
homogenous universe model by taking a noninteracting mixture of electromagnetic
and viscous radiating fluids whose viscous pressure satisfies a nonlinear
version of the Israel-Stewart transport equation. We establish an autonomous
system of equations by introducing normalized dimensionless variables. In order
to analyze stability of the system, we find corresponding critical points for
different values of the parameters. We also evaluate power-law scale factor
whose behavior indicates different phases of the universe model. It is
concluded that bulk viscosity as well as electromagnetic field enhances the
stability of accelerated expansion of the isotropic and homogeneous universe
model.Comment: 17 pages, 5 figures, accepted for publication in EPJ
Randall-Sundrum brane cosmology: modification of late-time cosmic dynamics by exotic matter
In this paper we show, through the study of concrete examples, that,
depending on the cosmic dynamics of the energy density of matter degrees of
freedom living in the brane, Randall-Sundrum (RS) brane effects can be
important not only at short distances (UV regime), but also at large
cosmological scales (IR regime). Our first example relies on the study, by
means of the dynamical systems tools, of a toy model based in a non-linear
electrodynamics (NLED) Lagrangian. Then we show that other, less elaborated
models, such as the inclusion of a scalar phantom field, and of a tachyon
phantom field -- trapped in the brane -- produce similar results. The form of
the RS correction seems to convert what would have been future attractors in
general relativity into saddle points. The above "mixing of scales" effect is
distinctive only of theories that modify the right-hand-side (matter part) of
the Friedmann equation, so that, for instance, DGP-brane models do not show
this feature.Comment: Latex, 12 pages, 9 eps figures. Title changed, discussion improved.
Version that matches the one published in CQ
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