Related papers: Quest for potentials in the quintessence scenario
We analyze the general conditions on the equation of state $w$ required for quantum fluctuations of a scalar field to produce a scale-invariant spectrum of density perturbations, including models which (in the four dimensional effective…
We investigate the observational consequences of the quintessence field rolling to and oscillating near a minimum in its potential, "if" it happens close to the present epoch (z<0.2). We show that in a class of models, the oscillations lead…
We discuss an alternative approach to quintessence modifying the usual equation of state of the cosmological fluid in order to see if going further than the approximation of perfect fluid allows to better reproduce the available data. We…
Over the last few years, a large family of cosmological attractor models has been discovered, which can successfully match the latest inflation-related observational data. Many of these models can also describe a small cosmological constant…
Applying the parametrization of dark energy density, we can construct directly independent-model potentials. In Born-Infeld type phantom dark energy model, we consider four special parametrization equation of state parameter. The evolutive…
The DESI collaboration have recently analyzed their first year of data, finding a preference for thawing dark energy scenarios when using parameterized equations of state for dark energy. We investigate whether this preference persists when…
Dynamical system analysis of a universe model which contains matter, radiation, and quintessence with exponential potential, $V \!(\phi)=V_{\!o} \, exp(-\alpha \kappa \phi) \,$, is studied in the light of recent observations and the…
We use linear perturbation theory to study perturbations in dynamical dark energy models. We compare quintessence and tachyonic dark energy models with identical background evolution. We write the corresponding equations for different…
Motivated by the apparent discrepancy between Cosmic Microwave Background measurements of the Hubble constant and measurements from Type-Ia supernovae, we construct a model for Dark Energy with equation of state $w = p / \rho < -1$,…
Negative lambda gravitational effective field theories dual to holographic CFTs have potentially realistic cosmological solutions. Generic cosmological solutions of these effective field theories have scalar field evolution that can lead to…
We explore the dynamics of dark energy models based on a Dirac-Born-Infeld (DBI) tachyonic action, studying a range of potentials. We numerically investigate the existence of tracking behaviour and determine the present-day value of the…
In this work we study a scale invariant gravity theory containing two scalar fields, dust particles and a measure defined from degrees of freedom independent of the metric. The integration of the degrees of freedom that define the measure…
We study the late-time evolution of the Universe where dark energy (DE) is presented by a barotropic fluid on top of cold dark matter (CDM). We also take into account the radiation content of the Universe. Here by the late stage of the…
Cosmological models with variable and modified equations of state for dark energy are confronted with observational data, including Type Ia supernovae, Hubble parameter data $H(z)$ from different sources, and observational manifestations of…
In this paper, we regard dilaton in Weyl-scaled induced gravitational theory as coupled Quintessence, which is called DCQ model by us. Parametrization of the dark energy model is a good method by which we can construct the scalar potential…
We explore unification of dark matter and dark energy in a theory containing a scalar field of non-Lagrangian type, obtained by direct insertion of a kinetic term into the energy-momentum tensor. This scalar is different from quintessence,…
Models where the dark energy is a scalar field with a non-standard Dirac-Born-Infeld (DBI) kinetic term are investigated. Scaling solutions are studied and proven to be attractors. The corresponding shape of the brane tension and of the…
We examine the prospects for the next generation of surveys aimed at elucidating the nature of dark energy. We review the methods that can be used to determine the redshift evolution of the dark energy equation of state parameter w,…
Observations have confirmed the accelerated expansion of the universe. The accelerated expansion can be modelled by invoking a cosmological constant or a dynamical model of dark energy. A key difference between these models is that the…
We study the spherical collapse model in dark energy cosmologies, in which dark energy is modelled as a minimally coupled scalar field. We first follow the standard assumption that dark energy does not cluster on the scales of interest.…