# Primordial Features from Linear to Nonlinear Scales

## TL;DR

This paper demonstrates that large-scale structure observations can surpass the cosmic microwave background in detecting primordial features, providing stronger constraints and extending the accessible frequency range for inflationary signatures.

## Contribution

It introduces a novel feature search method for galaxy surveys, applying it to BOSS data and forecasting significant improvements with future surveys like DESI and Euclid.

## Key findings

- Galaxy surveys can detect primordial features more robustly than CMB.
- New bounds on oscillatory features exceed Planck's sensitivity.
- Future surveys will greatly improve constraints on inflationary models.

## Abstract

Sharp features in the primordial power spectrum are a powerful window into the inflationary epoch. To date, the cosmic microwave background (CMB) has offered the most sensitive avenue to search for these signatures. In this paper, we demonstrate the power of large-scale structure observations to surpass the CMB as a probe of primordial features. We show that the signatures in galaxy surveys can be separated from the broadband power spectrum and are as robust to the nonlinear evolution of matter as the standard baryon acoustic oscillations. As a result, analyses can exploit a significant range of scales beyond the linear regime available in the datasets. We develop a feature search for large-scale structure, apply it to the final data release of the Baryon Oscillation Spectroscopic Survey and find new bounds on oscillatory features that exceed the sensitivity of Planck for a significant range of frequencies. Moreover, we forecast that the next generation of galaxy surveys, such as DESI and Euclid, will be able to improve current constraints by up to an order of magnitude over an expanded frequency range.