Dynamics of coupled phantom and tachyon fields

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Abstract

In this paper, we apply the dynamical analysis to a coupled phantom field with scaling potential taking particular forms of the coupling (linear and combination of linear), and present phase space analysis. We investigate if there exist late time accelerated scaling attractor that has the ratio of dark energy and dark matter densities of the order one. We observe that the scrutinized couplings cannot alleviate the coincidence problem, however acquire stable late time accelerated solutions. We also discuss coupled tachyon field with inverse square potential assuming linear coupling.

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Om diagnostic applied to scalar field models and slowing down of cosmic acceleration

M. Shahalam, Abhineet Agarwal, Sasha Sami (2015)

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The BICEP2 data and a single Higgs-like interacting tachyonic field

Murli Verma, Shankar Pathak (2013)

It is proposed that the recently announced BICEP2 value of tensor-to scalar ratio \(r\sim0.2\) can be explained as containing an extra contribution from the recent acceleration of the universe. In fact this contribution, being robust, recent and of much longer duration (by a large order of magnitude) may dominate the contribution from the inflationary origin. In a possible scenario, matter (dark or baryonic) and radiation etc. can emerge from a single Higgs-like tachyonic scalar field in the universe through a physical mechanism not yet fully known to us. The components interact among themselves to achieve the thermodynamical equilibrium in the evolution of the universe. The field potential for the present acceleration of the universe would give a boost to the amplitude of the tensor fluctuations of gravity waves generated by the early inflation and the net effects may be higher than the earlier PLANCK bounds. In the process, the dark energy, as a cosmological constant decays into creation of dark matter. The diagnostics for the three-component, spatially homogeneous tachyonic scalar field are discussed in detail. The components of the field with perturbed equation of state are taken to interact mutually and the conservation of energy for individual components gets violated. We study mainly the \(O_{m}(x)\) diagnostics with the observed set of \(H(z)\) values at various redshifts, and the dimensionless state-finders for these interacting components. This analysis provides a strong case for the interacting dark energy in our model.