Probing primordial features with future galaxy surveys

TL;DR

Future galaxy surveys combined with CMB data can effectively detect and constrain deviations from the simple power-law primordial power spectrum, enhancing our understanding of inflationary models.

Contribution

This paper forecasts the potential of upcoming galaxy surveys to probe primordial spectrum features beyond the standard power-law, using models motivated by inflation.

Findings

Galaxy surveys can significantly improve constraints on primordial spectrum deviations.

Combining galaxy surveys with CMB data enhances parameter estimation.

Future surveys like DESI, Euclid, and SPHEREx are promising for inflationary model testing.

Abstract

We study the capability of future measurements of the galaxy clustering power spectrum to probe departures from a power-law spectrum for primordial fluctuations. On considering the information from the galaxy clustering power spectrum up to quasi-linear scales, i.e. $k<0.1$ h Mpc$^{-1}$, we present forecasts for DESI, Euclid and SPHEREx in combination with CMB measurements. As examples of departures in the primordial power spectrum from a simple power-law, we consider four $Planck$ 2015 best-fits motivated by inflationary models with different breaking of the slow-roll approximation. These four representative models provide an improved fit to CMB temperature anisotropies, although not at statistical significant level. As for other extensions in the matter content of the simplest $\Lambda$CDM model, the complementarity of the information in the resulting matter power spectrum expected from these galaxy surveys and in the primordial power spectrum from CMB anisotropies can be effective in constraining cosmological models. We find that the three galaxy surveys can add significant information to CMB to better constrain the extra parameters of the four models considered.