Features in the primordial spectrum: new constraints from WMAP7+ACT data and prospects for Planck

TL;DR

This paper updates constraints on features in the primordial spectrum using WMAP7 and ACT data, finds no strong evidence for features but notes models with a step fit better, and discusses prospects for testing with Planck data.

Contribution

It provides new constraints on inflationary spectrum features with recent data and highlights the potential of Planck to further test these models.

Findings

No clear statistical evidence for features in the primordial spectrum.

Models with a step in the inflationary potential fit the data better than featureless models.

Upcoming Planck data will be able to test the step model predictions.

Abstract

We update the constraints on possible features in the primordial inflationary density perturbation spectrum by using the latest data from the WMAP7 and ACT Cosmic Microwave Background experiments. The inclusion of new data significantly improves the constraints with respect to older work, especially to smaller angular scales. While we found no clear statistical evidence in the data for extensions to the simplest, featureless, inflationary model, models with a step provide a significantly better fit than standard featureless power-law spectra. We show that the possibility of a step in the inflationary potential like the one preferred by current data will soon be tested by the forthcoming temperature and polarization data from the Planck satellite mission.