Testing an oscillatory behavior of dark energy

Abstract

The main aim of this work is to use a model-independent approach, along with late-time observational probes, to reconstruct the dark energy (DE) equation of state <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>w</a:mi></a:mrow><a:mrow><a:mi>DE</a:mi></a:mrow></a:msub><a:mo stretchy="false">(</a:mo><a:mi>z</a:mi><a:mo stretchy="false">)</a:mo></a:mrow></a:math>. Our analysis showed that, for a late time universe, <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"><e:msub><e:mi>w</e:mi><e:mrow><e:mi>DE</e:mi></e:mrow></e:msub></e:math> deviates from being a constant but in contrast exhibits an oscillatory behavior, hence both quintessence (<g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"><g:msub><g:mi>w</g:mi><g:mrow><g:mi>DE</g:mi></g:mrow></g:msub><g:mo>&gt;</g:mo><g:mo>−</g:mo><g:mn>1</g:mn></g:math>) and phantom (<i:math xmlns:i="http://www.w3.org/1998/Math/MathML" display="inline"><i:msub><i:mi>w</i:mi><i:mrow><i:mi>DE</i:mi></i:mrow></i:msub><i:mo>&lt;</i:mo><i:mo>−</i:mo><i:mn>1</i:mn></i:math>) regimes are equally allowed. In order to portray this oscillatory behavior, we explored various parametrizations for the equation of state and identified the closest approximation based on the goodness of fit with the data and the Bayesian evidence analysis. Our findings indicated that while all considered oscillating DE parametrizations provide a better fit to the data, when compared to the cosmological constant, they are penalized in the Bayesian evidence analysis due to the additional free parameters. Overall, the present article demonstrates that, in the low redshift regime, the equation of state of the DE prefers to be dynamical and oscillating. We anticipate that future cosmological probes will take a stand in this direction.