Degeneracy between primordial non-Gaussianity and interaction in the dark sector

TL;DR

This paper investigates how interactions between dark energy and dark matter can mimic primordial non-Gaussian signals in galaxy power spectra, proposing methods to distinguish between them using multi-redshift measurements.

Contribution

It introduces a class of interacting dark energy models and demonstrates how their effects on large-scale structure can be differentiated from primordial non-Gaussianity.

Findings

Dark sector interaction induces scale-dependent effects on large scales.

Effective non-Gaussianity can be estimated from interaction effects.

Multi-redshift measurements can disentangle dark sector effects from primordial signals.

Abstract

If dark energy and dark matter interact via exchange of energy and momentum, then this may affect the galaxy power spectrum on large scales. When this happens, it may be degenerate with the signal from primordial non-Gaussianity via scale-dependent bias. We consider a class of interacting dark energy models and show that the matter overdensity is scale-dependent on large scales. We estimate the effective non-Gaussianity arising from the large-scale effects of interaction in the dark sector. The signal of dark sector interaction can be disentangled from a primordial non-Gaussian signal by measuring the power at two redshifts.