Refining the nonlinear modelling of primordial oscillatory features

TL;DR

This paper develops a detailed nonlinear model for primordial oscillatory features in the matter power spectrum, including new analytical contributions, and validates these with simulations to aid future cosmological observations.

Contribution

It extends existing models by deriving analytical expressions with novel terms and compares them with simulations, enhancing understanding of nonlinear effects on primordial features.

Findings

Analytical expressions include mixed primordial and baryon acoustic oscillation terms.

Simulations confirm the small but significant nonlinear corrections.

Results provide a foundation for future detection of primordial oscillatory features.

Abstract

Primordial oscillatory features in the power spectrum of curvature perturbations are sensitive probes of the dynamics of the early Universe and can provide insights beyond the standard inflationary scenario. While these features have been the focus of extensive studies using cosmic microwave background anisotropy data, large-scale structure surveys now provide competitive constraints with the opportunity to probe their effects at smaller scales with higher precision. In this paper, we present a complete description of the nonlinear model for primordial oscillatory features in the context of time-sliced perturbation theory extending the results already presented in the literature. We derive analytical expressions including novel contributions such as the mixed term between primordial oscillations and baryon acoustic oscillations, and we also calculate the corrections arising from the specific envelope of the oscillatory pattern, corresponding to a scale-dependent amplitude. These results are compared with N-body simulations using the COLA method and show consistent behaviour across different scales. Although the corrections are found to be small, they represent an important step to fully characterising the nonlinear imprints of primordial features on the matter power spectrum. Our results offer new calculations to be tested with future cosmological surveys that seek to detect these subtle signatures in the matter distribution.