A test of the CPL parameterization for rapid dark energy equation of state transitions

TL;DR

This study evaluates the effectiveness of the CPL parameterization in modeling rapid dark energy transitions, finding it reliable except for certain recent, swift changes in the equation of state.

Contribution

It provides a detailed analysis of the CPL parameterization’s robustness in reconstructing complex dark energy models using simulated future observational data.

Findings

CPL accurately reconstructs slow and moderate dark energy transitions.

Biases appear in rapid, recent transitions ($z<2.5$).

CPL is reliable for most scenarios except specific rapid changes.

Abstract

We test the robustness and flexibility of the Chevallier-Polarski-Linder (CPL) parameterization of the Dark Energy equation of state $w(z)=w_0+w_a \frac{z}{1+z}$ in recovering a four-parameter step-like fiducial model. We constrain the parameter space region of the underlying fiducial model where the CPL parameterization offers a reliable reconstruction. It turns out that non negligible biases leak into the results for recent ($z<2.5$) rapid transitions, but that CPL yields a good reconstruction in all other cases. The presented analysis is performed with supernova Ia data as forecasted for a space mission like SNAP/JDEM, combined with future expectations for the CMB shift parameter $R$ and the BAO parameter $A$.