Searching for primordial localized features with CMB and LSS spectra

TL;DR

This study searches for primordial localized features in the inflationary period using CMB and LSS data, finding oscillatory patterns and marginal evidence for a non-zero amplitude, with joint data analysis improving constraints.

Contribution

It introduces a combined analysis of CMB and LSS data to detect primordial features, confirming and refining previous findings with enhanced parameter constraints.

Findings

Oscillatory patterns found in both Planck and WiggleZ data.

Joint analysis constrains oscillation frequency and suggests marginally non-zero amplitude.

WiggleZ data mildly increases the significance of the detected feature.

Abstract

Inspired by the study of mild transient reductions in the speed of sound of the adiabatic mode during inflation, we search for a primordial localized feature imprinted in cosmic microwave background and large-scale structure formation observables. We find some common oscillatory patterns both in the Planck CMB temperature-temperature power spectrum and the WiggleZ galaxy spectrum. By performing independent searches with these two data sets, we find a coincidence in the most significant mode previously found by Ach\'ucarro et al. 2013 by using only Planck data. Furthermore, the joint data analysis shows that the oscillation frequency of the feature gets better constrained, and the amplitude marginally deviates from zero, unlike what was observed using only Planck data. Besides the parameter estimation, we also discuss the Bayesian evidence. The addition of WiggleZ data mildly enhances the significance of the best mode found in the Planck data.