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Garcia-Salcedo R.,Research Center en Ciencia Aplicada y Tecnologia Avanzada Legaria Del | Gonzalez T.,Santa Clara University | Moreno C.,University of Guadalajara | Napoles Y.,Santa Clara University | And 2 more authors.
Journal of Cosmology and Astroparticle Physics | Year: 2010

We apply the dynamical systems tools to study the asymptotic properties of a cosmological model based on a non-linear modification of General Relativity in which the standard Einstein-Hilbert action is replaced by one of Dirac-Born-Infeld type. It is shown that the dynamics of this model is extremely rich: there are found equilibrium points in the phase space that can be associated with matter-dominated, matter-curvature scaling, de Sitter, and even phantom-like solutions. Depending on the value of the overall parameters the dynamics in phase space can show multi-attractor structure into the future (multiple future attractors may co-exist). This is a consequence of bifurcations in control parameter space, showing strong dependence of the model's dynamical properties on the free parameters. Contrary to what is expected from non-linear modifications of general relativity of this kind, removal of the initial spacetime singularity is not a generic feature of the corresponding cosmological model. Instead, the starting point of the cosmic dynamics - the past attractor in the phase space - is a state of infinitely large value of the Hubble rate squared, usually associated with the big bang singularity. © 2010 IOP Publishing Ltd and SISSA.


Garcia-Salcedo R.,Research Center en Ciencia Aplicada y Tecnologia Avanzada Legaria Del | Gonzalez T.,Research Center Estudios Avanzadas Del Ipn | Moreno C.,University of Guadalajara | Quiros I.,University of Guanajuato
Classical and Quantum Gravity | Year: 2011

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 system tools, of a toy model based in a nonlinear 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, Dvali-Gabadadze-Porrati-brane models do not show this feature. © 2011 IOP Publishing Ltd.


Garcia-Salcedo R.,Research Center en Ciencia Aplicada y Tecnologia Avanzada Legaria Del | Gonzalez T.,University of Guanajuato | Quiros I.,University of Guadalajara | Thompson-Montero M.,University of Guadalajara
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We explore the whole phase space of the so-called Veneziano/QCD ghost dark energy models where the dynamics of the inner trapping horizon is ignored and also the more realistic models where the time dependence of the horizon is taken into consideration. We pay special attention to the choice of phase space variables leading to bounded and compact phase space so that no critical point of physical interest is missing. It is demonstrated that ghost dark energy is not a suitable candidate to explain the presently accepted cosmological paradigm, since no critical point associated with matter dominance is found in the physical phase space of the model. A transient stage of matter dominance - responsible for the observed amount of cosmic structure - is an essential ingredient of the accepted cosmological paradigm. The above drawback is in addition to the well-known problem with classical instability against small perturbations of the background density originated from negativity of the sound speed squared. © 2013 American Physical Society.


Avelino A.,University of Guanajuato | Garcia-Salcedo R.,Research Center en Ciencia Aplicada y Tecnologia Avanzada Legaria Del | Gonzalez T.,University of Guanajuato | Nucamendi U.,Universidad Michoacana de San Nicolás de Hidalgo | Quiros I.,University of Guadalajara
Journal of Cosmology and Astroparticle Physics | Year: 2013

By means of a combined use of the type Ia supernovae and H(z) data tests, together with the study of the asymptotic properties in the equivalent phase space - through the use of the dynamical systems tools - we demonstrate that the bulk viscous matter-dominated scenario is not a good model to explain the accepted cosmological paradigm, at least, under the parametrization of bulk viscosity considered in this paper. The main objection against such scenarios is the absence of conventional radiation and matter-dominated critical points in the phase space of the model. This entails that radiation and matter dominance are not generic solutions of the cosmological equations, so that these stages can be implemented only by means of unique and very specific initial conditions, i. e., of very unstable particular solutions. Such a behavior is in marked contradiction with the accepted cosmological paradigm which requires of an earlier stage dominated by relativistic species, followed by a period of conventional non-relativistic matter domination, during which the cosmic structure we see was formed. Also, we found that the bulk viscosity is positive just until very late times in the cosmic evolution, around z < 1. For earlier epochs it is negative, been in tension with the local second law of thermodynamics. © 2013 IOP Publishing Ltd and Sissa Medialab srl.

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