Related papers: Assessing cosmological evidence for non-minimal co…
Current data in the form of baryon acoustic oscillation, supernova, and cosmic microwave background distances prefer a cosmology that accelerates more strongly than $\Lambda$CDM at $z\approx0.5-1.5$, and more weakly at $z\lesssim0.5$. We…
We study a dark energy scenario in the presence of a tachyon field $\phi$ with potential $V(\phi)$ and a barotropic perfect fluid. The cosmological dynamics crucially depends on the asymptotic behavior of the quantity…
We perform a dynamical analysis for the exponential scalar field with non-minimally derivative coupling. For the quintessence case, the stable fixed points are the same with and without the non-minimally derivative coupling. For the phantom…
In this article, we investigate the existence of accelerating scaling solutions in coupled phantom cosmology without assuming any specific potential for the phantom scalar field. The coupling between phantom dark energy and dark matter is…
We study a new model of scalar field with a general non-minimal kinetic coupling to itself and to the curvature, as a source of dark energy, and analyze the cosmological dynamics of this model and the issue of accelerated expansion. A wide…
We analyze a cosmological solution to the field equations of a modified gravity model where curvature and matter are nonminimally coupled. The current Universe's accelerated expansion is driven by a cosmological constant while the impact of…
We show how the scalar field, a candidate of quintessence, in a proposed model of the scalar-tensor theories of gravity provides a way to understand a small but nonzero cosmological constant as indicated by recent observations. A particular…
In this Thesis I discuss several recent results obtained using the CMB spectra measured by Planck and several other cosmological probes. Extensions of the $\Lambda$CDM model are studied, including the presence of an additional sterile…
Many models have been studied that contain more than one species of dark matter and some of these couple the Cold Dark Matter (CDM) to a light scalar field. In doing this we introduce additional long range forces, which in turn can…
The rapid oscillating scalar field is considered as the quintessence in the framework of nonminimal kinetic coupling model. The scalar field behaves like a perfect fluid with a variable equation of state parameter which can be expressed as…
We present updated constraints on an interacting dark energy - dark matter model with pure momentum transfer, where dark energy is in the form of a quintessence scalar field with an exponential potential. We run a suite of MCMC analyses…
We examine the embedding of dark energy in high energy models based upon supergravity and extend the usual phenomenological setting comprising an observable sector and a hidden supersymmetry breaking sector by including a third sector…
We numerically and analytically explore the background cosmological dynamics of multifield dark energy with highly nongeodesic or "spinning" field-space trajectories. These extensions of standard single-field quintessence possess appealing…
We study structure formation in non-minimally coupled dark energy models, where there is a coupling in the Lagrangian between a quintessence scalar field and gravity via the Ricci scalar. We consider models with a range of different…
We study the effect of an explicit interaction between two scalar fields components describing dark matter in the context of a recent proposal framework for interaction. We find that, even assuming a very small coupling, it is sufficient to…
We investigate a coupled quintessence cosmological model in which a dark-energy scalar field with an exponential potential interacts directly with a dark-matter fluid through a dissipative term inspired by warm inflation. The evolution…
Observations of distant supernovae indicate that the Universe is now in a phase of accelerated expansion the physical cause of which is a mystery. Formally, this requires the inclusion of a term acting as a negative pressure in the…
In the past years 'quintessence' models have been considered which can produce the accelerated expansion in the universe suggested by recent astronomical observations. One of the key differences between quintessence and a cosmological…
Power-law cosmology with scale factor as power of cosmic time, $a \propto t^{\a}$, is investigated. We review and discuss value of $\a$ obtained from various types of observation. Considering dark energy dominant era in late universe from…
We apply the tools of the dynamical system theory in order to revisit and uncover the structure of a nongravitational interaction between pressureless dark matter and dark energy described by a scalar field $\phi$. For a coupling function…