arXiv subjects

Wompherdeiki Khyllep

Publications and source records attributed to Wompherdeiki Khyllep.

22 records · Page 2Linked to original sources

arXiv2017

Dynamical analysis of interacting dark energy model in the framework of particle creation mechanism

In this work we present the cosmological dynamics of interacting dark energy models in the framework of particle creation mechanism. The particle creation mechanism presented here describes the true non equilibrium thermodynamics of the universe. In spatially flat Friedmann-Lema{\^ı}tre-Robertson-Walker universe considered here, the dissipative bulk viscous pressure is due to the non conservation of particle number. For simplicity, we assume that the creation of perfect fluid particles to be isentropic (adiabatic) and consequently the viscous pressure obeys a linear relationship with particle creation rate. Due to complicated nature of the Einstein's field equations, dynamical systems analysis has been performed to understand deeply about the cosmological dynamics. We have found some interesting cosmological scenarios like late-time evolution of universe dominated by dark energy which could mimic quintessence, cosmological constant or phantom field through a dark matter dominated era. We also obtained a possibility of crossing the phantom divide line which is favored by observations.

gr-qc↗

arXiv2017

Cosmological dynamics of scalar fields with kinetic corrections: Beyond the exponential potential

We expand the dynamical systems investigation of cosmological scalar fields characterised by kinetic corrections presented in [N. Tamanini, Phys. Rev. D 89 (2014) 083521]. In particular we do not restrict the analysis to exponential potentials only, but we consider arbitrary scalar field potentials and derive general results regarding the corresponding cosmological dynamics. Two specific potentials are then used as examples to show how these models can be employed not only to describe dark energy, but also to achieve dynamical crossing of the phantom barrier at late times. Stability and viability issues at the classical level are also discussed.

gr-qc↗

arXiv2017

Scalar-Fluid interacting dark energy: cosmological dynamics beyond the exponential potential

We extend the dynamical systems analysis of Scalar-Fluid interacting dark energy models performed in C. G. Boehmer et al, Phys. Rev. D 91, 123002 (2015), by considering scalar field potentials beyond the exponential type. The properties and stability of critical points are examined using a combination of linear analysis, computational methods and advanced mathematical techniques, such as centre manifold theory. We show that the interesting results obtained with an exponential potential can generally be recovered also for more complicated scalar field potentials. In particular, employing power-law and hyperbolic potentials as examples, we find late time accelerated attractors, transitions from dark matter to dark energy domination with specific distinguishing features, and accelerated scaling solutions capable of solving the cosmic coincidence problem.

gr-qc↗

arXiv2016

Late time accelerated scaling attractors in DGP (Dvali-Gabadadze-Porrati) braneworld

In the evolution of late universe, the main source of matter are Dark energy and Dark matter. They are indirectly detected only through their gravitational manifestations. So the possibility of interaction with each other without violating observational restrictions is not ruled out. With this motivation, we investigate the dynamics of DGP braneworld where source of dark energy is a scalar field and it interacts with matter source. Since observation favours phantom case more, we have also studied the dynamics of interacting phantom scalar field. In non interacting DGP braneworld there are no late time accelerated scaling attractors and hence cannot alleviate Coincidence problem. In this paper, we shall show that it is possible to get late time accelerated scaling solutions. The phase space is studied by taking two categories of potentials (Exponential and Non exponential functions). The stability of critical points are examined by taking two specific interactions. The first interaction gives late time accelerated scaling solution for phantom field only under exponential potential, while for second interaction we do not get any scaling solution. Furthermore, we have shown that this scaling solution is also classically stable.

gr-qc↗