Exploring Parameter Constraints on Quintessential Dark Energy: the Pseudo-Nambu Goldstone Boson Model

TL;DR

This paper assesses how future dark energy experiments can constrain the parameters of the Pseudo-Nambu Goldstone Boson quintessence model, showing that larger experiments could decisively distinguish it from a cosmological constant.

Contribution

It provides a forecast of the constraining power of future experiments on the PNGB dark energy model using a standardized methodology and MCMC analysis.

Findings

Stage 4 experiments can rule out a cosmological constant at 3 sigma.

Different experimental stages have comparable constraining power to existing dark energy parametrizations.

Future data can significantly narrow down PNGB model parameters.

Abstract

We analyze the constraining power of future dark energy experiments for Pseudo-Nambu Goldstone Boson (PNGB) quintessence. Following the Dark Energy Task Force methodology, we forecast data for three experimental ``stages'': Stage 2 represents in-progress projects relevant to dark energy; Stage 3 refers to medium sized experiments; Stage 4 comprises larger projects. We determine the posterior probability distribution for the parameters of the PNGB model using Markov Chain Monte Carlo analysis. Utilizing data generated on a $\Lambda CDM$ cosmology, we find that the relative power of the different data stages on PNGB quintessence is roughly comparable to the DETF results for the $w_0-w_a$ parametrization of dark energy. We also generate data based on a PNGB cosmological model that is consistent with a $\Lambda CDM$ fiducial model at Stage 2. We find that Stage 4 data based on this PNGB fiducial model will rule out a cosmological constant by at least $3 \sigma$.