50 research outputs found
On the consistency of tachyon warm inflation with viscous pressure
We obtain conditions for the existence of an attractor in the system of
equations describing a tachyon warm inflationary model with bulk viscosity
taken into account. When these conditions are met the evolution approaches
slow-roll regime. We present the primordial power spectrum for the tachyon
field by considering a dissipation coefficient depending on the scalar field
and temperature.Comment: 12 page
Intermediate Inflation in the Jordan-Brans-Dicke Theory
We present an intermediate inflationary stage in a Jordan-Brans-Dicke theory.
In this scenario we analyze the quantum fluctuations corresponding to adiabatic
and isocurvature modes. The model is compared to that described by using the
intermediate model in Einstein General Relativity theory. We assess the status
of this model in light of the WMAP7 data.Comment: Proceedings of I CosmoSul - Cosmology and Gravitation in Southern
Cone (Rio de Janeiro, 2011). Eds: J. S. Alcaniz, S. Carneiro, L. P. Chimento,
S. del Campo, J. C. Fabris, J. A. S. Lima and W. Zimdah
AIC and BIC for cosmological interacting scenarios
In this work we study linear and non-linear cosmological interactions, which
depend on dark matter and dark energy densities in the framework of General
Relativity. By using the Akaike information criterion (AIC) and the Bayesian
information criterion (BIC) with data from SnIa (Union 2.1 and binned JLA),
H(z), BAO and CMB we compare the interacting models among themselves and
analyze whether more complex interacting models are favored by these criteria.
In this context, we find some suitable interactions that alleviate the
coincidence problem.Comment: 24 pages, 4 figures, minor changes, file replaced to match published
version to appear in EPJ
Nonminimal Inflation on the Randall-Sundrum II Brane with Induced Gravity
We study an inflation model that inflaton field is non-minimally coupled to
the induced scalar curvature on the Randall-Sundrum (RS) II brane. We
investigate the effects of the non-minimal coupling on the inflationary
dynamics of this braneworld model. Our study shows that the number of e-folds
decreases by increasing the value of the non-minimal coupling. We compare our
model parameters with the minimal case and also with recent observational data.
In comparison with recent observation, we obtain a constraint on the values
that the non-minimal coupling attains.Comment: 15 pages, 5 figure
On sign-changeable interaction in FLRW cosmology
We investigate an interacting two-fluid model in a spatially flat
Friedmann-Lema\^itre-Robertson-Walker (FLRW) Universe, when the energy transfer
between these two dark components is produced by a factorisable nonlinear
sign-changeable interaction depending linearly on the energy density and
quadratically on the deceleration parameter. We solve the source equation and
obtain the effective energy densities of the dark sector and their components.
We show that the effective equation of state of the dark sector includes some
of the several kind of Chaplygin gas equations of state as well as a
generalization of the polytropic equation of state. We use bayesian statistics
methods to constrain free parameters in the models during its most recent
evolution considering supernovae type Ia and measurements of the Hubble
expansion rate. The resulting constraints provide new information on
sign-changeable interactions, its equivalences and compatibility with previous
models and novel late time universe dynamics.Comment: 8 figure
Modified holographic Ricci interacting dark energy models: dynamical system analysis and bayesian comparison
We perform a dynamical system analysis and a Bayesian model selection for a
new set of interacting scenarios in the framework of modified holographic Ricci
dark energy models (MHR-IDE). The dynamical analysis shows a modified radiation
epoch and a late-time attractor corresponding to dark energy. We use a
combination of background data such as type Ia supernovae, cosmic chronometers,
cosmic microwave background, and baryon acoustic oscillations measurements. We
find evidence against all the MHR-IDE scenarios studied with respect to
CDM, when the full joint analysis is considered.Comment: 21 page