Neglecting Primordial non-Gaussianity Threatens Future Cosmological Experiment Accuracy

Understand

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.