Latest inflation model constraints from cosmic microwave background measurements

TL;DR

This paper updates constraints on single-field inflation models using WMAP5 data, confirming the consistency of a Harrison-Zel'dovich spectrum, no running, and tight limits on tensor perturbations, refining previous results.

Contribution

It provides the latest cosmological constraints on inflation models based on WMAP5 data, confirming previous findings and tightening bounds on tensor modes and potential forms.

Findings

WMAP5 data are consistent with a Harrison-Zel'dovich spectrum.

No evidence for running of the spectral index.

Upper limit on tensor-to-scalar ratio r < 0.35.

Abstract

In this addendum to Phys.Rev. D74 (2006) 023502, we present an update of cosmological constraints on single-field inflation in light of the Wilkinson Microwave Ansiotropy Probe satellite mission five-year results (WMAP5). We find that the cosmic microwave background data are quite consistent with a Harrison-Zel'dovich primordial spectrum with no running and zero tensor amplitude. We find that the three main conclusions of our analysis of the WMAP three-year data (WMAP3) are consistent with the WMAP5 data: (1) the Harrison--Zel'dovich model is within the 95% confidence level contours; (2) there is no evidence for running of the spectral index of scalar perturbations; (3) From the WMAP 5 data alone, potentials of the form $V \propto \phi^p$ are consistent with the data for $p = 2$, and are ruled out for $p = 4$. Furthermore, consistent with our WMAP3 analysis, we find no evidence for primordial tensor perturbations, this time with a 95% confidence upper limit of $r < 0.4$ for the WMAP5 data alone, and $r < 0.35$ for the WMAP5 data taken in combination with the Arcminute Cosmology Bolometer Array (ACBAR).