Bayesian model selection on Scalar $epsilon$-Field Dark Energy. (arXiv:2009.01904v2 [gr-qc] UPDATED)
<a href="http://arxiv.org/find/gr-qc/1/au:+Vazquez_J/0/1/0/all/0/1">J. Alberto Vázquez</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Tamayo_D/0/1/0/all/0/1">David Tamayo</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Sen_A/0/1/0/all/0/1">Anjan A. Sen</a>, <a href="http://arxiv.org/find/gr-qc/1/au:+Quiros_I/0/1/0/all/0/1">Israel Quiros</a>
The main aim of this paper is to analyse minimally-coupled scalar-fields —
quintessence and phantom — as the main candidates to explain the accelerated
expansion of the universe and compare its observables to current cosmological
observations; as a byproduct we present its python module. This work includes a
parameter $epsilon$ which allows to incorporate both quintessence and phantom
fields within the same analysis. Examples of the potentials, so far included,
are $V(phi)=V_0phi^{mu}e^{beta phi^alpha}$ and $V(phi)=V_0(cosh(alpha
phi) + beta)$ with $alpha$, $mu$ and $beta$ being free parameters, but the
analysis can be easily extended to any other scalar field potential. Additional
to the field component and the standard content of matter, the code also
incorporates the contribution from spatial curvature ($Omega_k$), as it has
been the focus in recent studies. The analysis contains the most up-to-date
datasets along with a nested sampler to produce posterior distributions along
with the Bayesian evidence, that allows to perform a model selection. In this
work we constrain the parameter-space describing the two generic potentials,
and amongst several combinations, we found that the best-fit to current
datasets is given by a model slightly favouring the quintessence field with
potential $V(phi)=V_0phi^mu e^{beta phi}$ with $beta=0.22pm 1.56$,
$mu=-0.41pm 1.90$, and slightly closed curvature
$Omega_{k,0}=-0.0016pm0.0018$, which presents deviations of $1.6sigma$ from
the standard LCDM model. Even though this potential contains three extra
parameters, the Bayesian evidence $mathcal{B}_{L,phi} =2.0$ is unable to
distinguish it compared to the LCDM with curvature
($Omega_{k,0}=0.0013pm0.0018$). The potential that provides the minimal
Bayesian evidence corresponds to $V(phi)=V_0 cosh(alphaphi)$ with
$alpha=-0.61pm1.36$.
The main aim of this paper is to analyse minimally-coupled scalar-fields —
quintessence and phantom — as the main candidates to explain the accelerated
expansion of the universe and compare its observables to current cosmological
observations; as a byproduct we present its python module. This work includes a
parameter $epsilon$ which allows to incorporate both quintessence and phantom
fields within the same analysis. Examples of the potentials, so far included,
are $V(phi)=V_0phi^{mu}e^{beta phi^alpha}$ and $V(phi)=V_0(cosh(alpha
phi) + beta)$ with $alpha$, $mu$ and $beta$ being free parameters, but the
analysis can be easily extended to any other scalar field potential. Additional
to the field component and the standard content of matter, the code also
incorporates the contribution from spatial curvature ($Omega_k$), as it has
been the focus in recent studies. The analysis contains the most up-to-date
datasets along with a nested sampler to produce posterior distributions along
with the Bayesian evidence, that allows to perform a model selection. In this
work we constrain the parameter-space describing the two generic potentials,
and amongst several combinations, we found that the best-fit to current
datasets is given by a model slightly favouring the quintessence field with
potential $V(phi)=V_0phi^mu e^{beta phi}$ with $beta=0.22pm 1.56$,
$mu=-0.41pm 1.90$, and slightly closed curvature
$Omega_{k,0}=-0.0016pm0.0018$, which presents deviations of $1.6sigma$ from
the standard LCDM model. Even though this potential contains three extra
parameters, the Bayesian evidence $mathcal{B}_{L,phi} =2.0$ is unable to
distinguish it compared to the LCDM with curvature
($Omega_{k,0}=0.0013pm0.0018$). The potential that provides the minimal
Bayesian evidence corresponds to $V(phi)=V_0 cosh(alphaphi)$ with
$alpha=-0.61pm1.36$.
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