Constraining dark energy interacting models with WMAP

We use observations of cosmic microwave background anisotropies, supernova luminosities and the baryon acoustic oscillation signal in the galaxy distribution to constrain the cosmological parameters in a simple interacting dark energy model with a time-varying equation of state. Using a Monte Carlo Markov Chain technique we determine the posterior likelihoods. Constraints from the individual data sets are weak, but the combination of the three data sets confines the interacti...

In this paper we study a model of interacting dark energy - dark matter where the ratio between these components is not constant, changing from early to late times in such a way that the model can solve or alleviate the cosmic coincidence problem (CP). The interaction arises from an assumed relation of the form $\rho_x \propto \rho_d^\alpha$, where $\rho_x$ and $\rho_d$ are the energy densities of dark energy and dark matter components, respectively, and $\alpha$ is a free pa...

The recent observations support that our universe is flat and expanding with acceleration. A quintessence model with a general relation between the quintessence potential and the quintessence kinetic energy was proposed to explain the phenomenon. The dark energy potential includes both the hyperbolic and the double exponential potentials. We analyze this model in detail by using the recent supernova and the first year Wilkinson Microwave Anisotropy Probe (WMAP) observations. ...

In this paper we use the recently released Type Ia Supernova (SNIa) data to constrain the interactions between the neutrinos and the dark energy scalar fields. In the analysis we take the dark energy scalars to be either Quintessence-like or Phantom-like. Our results show the data mildly favor a model where the neutrinos couple to a phantom-like dark energy scalar, which implies the equation of state of the coupled system behaves like Quintom scenario in the sense of paramete...

We consider an extension of the holographic Ricci dark energy model by introducing an interaction between dark energy and matter. In this model, the dark energy density is given by $rho_{Lambda}=-frac{1}{2}alpha M_{p}^{2}{R}$, where ${R}$ is the Ricci scalar curvature, $M_{p}$ is the reduced Planck mass, and $alpha$ is a dimensionless parameter. The interaction rate is given by $Q=gamma H rho_{Lambda}$, where $H$ is the Hubble expansion rate, and $gamma$ is a dimensionless pa...

We examine the effects of possible phenomenological interactions between dark energy and dark matter on cosmological parameters and their efficiency in solving the coincidence problem. We work with two simple parameterizations of the dynamical dark energy equation of state and the constant dark energy equation of state. Using observational data coming from the new 182 Gold type Ia supernova samples, the shift parameter of the Cosmic Microwave Background given by the three-yea...

New observations of Cosmic Microwave Background Anisotropies, Supernovae luminosity distances and Galaxy Clustering are sharpening our knowledge about dark energy. Here we present the latest constraints.

Non-gravitational interaction between two barotropic dark fluids, namely the pressureless dust and the dark energy in a spatially flat Friedmann-Lema\^{i}tre-Robertson-Walker model has been discussed. It is shown that for the interactions which are linear in terms the energy densities of the dark components and their first order derivatives, the net energy density is governed by a second order differential equation with constant coefficients. Taking a generalized interaction,...

In this talk we present a model of the universe in which dark energy is modelled explicitely with both a dynamical quintessence field and a cosmological constant. Our results confirm the possibility of a collapsing universe (for a given region of the parameter space), which is advantageous for an adequate formulation of both perturbative quantum field and string theories. We have also reproduced the measurements of modulus distance from supernovae with good accuracy.

We consider a self-consistent and physical approach to interacting dark energy models described by a Lagrangian, and identify a new class of models with variable dark energy sound speed. We show that if the interaction between dark energy in the form of quintessence and cold dark matter is purely momentum exchange this generally leads to a dark energy sound speed that deviates from unity. Choosing a specific sub-case, we study its phenomenology by investigating the effects of...