Cosmological Constraints on Isocurvature and Tensor Perturbations

TL;DR

This paper analyzes cosmological data to constrain primordial isocurvature and tensor perturbations, finding current observations favor adiabatic initial conditions and setting upper limits on non-adiabatic contributions, with implications for theoretical models.

Contribution

It provides updated constraints on isocurvature and tensor modes from recent observations and applies these to specific theoretical models like axion and curvaton scenarios.

Findings

Current data are consistent with purely adiabatic initial conditions.

Upper limits are established on isocurvature and tensor perturbation contributions.

Constraints are applied to axion and curvaton models, informing their viability.

Abstract

We investigate cosmological constraints on primordial isocurvature and tensor perturbations, using recent observations of the cosmic microwave background and the large scale structure. We find that present observations are consistent with purely adiabatic initial conditions for the structure formation under any priors on correlations of isocurvature modes, and upper limits on the contribution of isocurvature and tensor perturbations are presented. We also apply the obtained constraints to some specific theoretical models, axion isocurvature perturbation models and curvaton models, and give some implications for theoretical models.