Neglecting Primordial non-Gaussianity Threatens Future Cosmological Experiment Accuracy

TL;DR

Neglecting even small primordial non-Gaussianities in future galaxy surveys can lead to significant biases in cosmological parameter estimation, threatening the accuracy of upcoming cosmological experiments.

Contribution

This paper highlights the importance of accounting for primordial non-Gaussianity in cosmological analyses to avoid systematic biases.

Findings

Neglecting primordial non-Gaussianity introduces biases in parameter reconstruction.

Current limits on non-Gaussianity are sufficient to impact future surveys.

Proper modeling of non-Gaussianity is crucial for accurate cosmology.

Abstract

Future galaxy redshift surveys aim at probing the clustering of the cosmic large-scale structure with unprecedented accuracy, thus complementing cosmic microwave background experiments in the quest to deliver the most precise and accurate picture ever of our Universe. Analyses of such measurements are usually performed within the context of the so-called vanilla LCDM model - the six-parameter phenomenological model which, for instance, emerges from best fits against the recent data obtained by the Planck satellite. Here, we show that such an approach is prone to subtle systematics when the Gaussianity of primordial fluctuations is concerned. In particular, we demonstrate that, if we neglect even a tiny amount of primordial non-Gaussianity - fully consistent with current limits - we shall introduce spurious biases in the reconstruction of cosmological parameters. This is a serious issue that must be properly accounted for in view of accurate (as well as precise) cosmology.