Related papers: Measuring deviations from a cosmological constant:…
Cosmological observations are normally fit under the assumption that the dark sector can be decomposed into dark matter and dark energy components. However, as long as the probes remain purely gravitational, there is no unique decomposition…
Quintessence is a canonical scalar field introduced to explain the late-time cosmic acceleration. The cosmological dynamics of quintessence is reviewed, paying particular attention to the evolution of the dark energy equation of state w.…
Constraining the dark energy equation of state, $w_x(z)$, is one of the main issues of current and future cosmological surveys. In practice, this requires making assumptions about the evolution of $w_x$ with redshift $z$, which can be…
We propose and implement a novel test to assess deviations from well-established concordance $\Lambda$CDM cosmology while inferring dark energy properties. In contrast to the commonly implemented parametric forms of the dark energy…
Recent measurements suggest our universe has a substantial dark energy component, which is usually interpreted in terms of a cosmological constant. Here we examine how much the form of this dark energy can be modified while still retaining…
We derive a model of dark energy which evolves with time via the scale factor. The equation of state $\omega=(1-2\alpha)/(1+2\alpha)$ is studied as a function of a parameter $\alpha$ introduced in this model. In addition to the recent…
The background evolution of an accelerated, dark energy dominated universe is aptly described by non-canonical tachyon scalar field models. The accelerated expansion of the universe is determined by the choice of a suitable scalar field…
Despite our present-day inability to predict the topology of the universe it is expected that we should be able to detect it in the near future. A nontrivial detectable topology of the space section of the universe can be probed for all…
A comparative study of various parametrizations of the dark energy equation of state $w(z)$ and its variation with the redshift is made. Astrophysical constraints from 'integrated tracking' are laid down to test the physical viability and…
One of the most fundamental questions in cosmology is if dark energy is related just to a constant or it is something more complex. In this work, we call the attention to the fact that, under very general conditions, dark energy can be…
A six parameter cosmological model, involving a vacuum energy density that is extremely tiny compared to fundamental particle physics scales, describes a large body of increasingly accurate astronomical data. In a first part of this brief…
The evolution of scalar perturbations is studied for 2-component (non-relativistic matter and dark energy) cosmological models at the linear and non-linear stages. The dark energy is assumed to be the scalar field with either classical or…
In this work, we study tracker phantom dark energy models with a general parameterization of the scalar potentials. Our analysis also considers the scenario of having both phantom field and the cosmological constant as the dark energy…
We explore the recently introduced statefinder parameters. After reviewing their basic properties, we calculate the statefinder parameters for a variety of cosmological models, and investigate their usefulness as a means of theoretical…
Early dark energy (EDE) models are a class of quintessence dark energy with a dynamically evolving scalar field which display a small but non-negligible amount of dark energy at the epoch of matter-radiation equality. Compared with a…
This article discusses a dark energy cosmological model in the standard theory of gravity - general relativity with a broad scalar field as a source. Exact solutions of Einstein's field equations are derived by considering a particular form…
A hypothetical dark energy component may have an equation of state that is different from a cosmological constant and possibly even changing in time. The spacing of the cosmic microwave background peaks is sensitive to the ratio of the…
In this present work, we try to build up a cosmological model using a non-canonical scalar field within the framework of a spatially flat FRW space-time. In this context, we have considered four different parametrizations of the equation of…
For a general dark-energy equation of state, we estimate the maximum possible radius of massive structures that are not destabilized by the acceleration of the cosmological expansion. A comparison with known stable structures constrains the…
A new bound dark energy, BDE, cosmology has been proposed where the dark energy is the binding energy between light meson fields that condense a few tens of years after the big bang. It is reported that the correct dark energy density…