A new signature of primordial non-Gaussianities from the abundance of galaxy clusters

TL;DR

This paper explores how primordial non-Gaussianities influence galaxy cluster abundance and shows that neglecting them can lead to false signals of dark energy evolution.

Contribution

It introduces a new signature of primordial non-Gaussianities in galaxy cluster counts and demonstrates its impact on dark energy parameter reconstruction.

Findings

Primordial non-Gaussianities affect galaxy cluster abundance.

Ignoring non-Gaussianities can mimic dark energy evolution.

A discontinuity appears in the reconstructed dark energy equation of state.

Abstract

The evolution with time of the abundance of galaxy clusters is very sensitive to the statistical properties of the primordial density perturbations. It can thus be used to probe small deviations from Gaussianity in the initial conditions. The characterization of such deviations would help distinguish between different inflationary scenarios, and provide us with information on physical processes which took place in the early Universe. We have found that when the information contained in the galaxy cluster counts is used to reconstruct the dark energy equation of state as a function of redshift, assuming erroneously that no primordial non-Gaussianities exist, an apparent evolution with time in the effective dark energy equation of state arises,characterized by the appearance of a clear discontinuity.