Forecasting isocurvature models with CMB lensing information: axion and curvaton scenarios

TL;DR

This paper investigates how future astronomical data, especially CMB lensing, can improve constraints on isocurvature primordial fluctuations predicted by axion and curvaton inflation models, highlighting the importance of lensing information.

Contribution

It demonstrates that CMB lensing significantly enhances parameter estimation accuracy and helps break degeneracies in isocurvature models using Fisher matrix forecasts.

Findings

CMB lensing improves parameter constraints by up to 20%.

Lensing information helps break degeneracies between isocurvature amplitude and correlation phase.

Future data can better constrain isocurvature contributions in inflationary models.

Abstract

Some inflationary models predict the existence of isocurvature primordial fluctuations, in addition to the well known adiabatic perturbation. Such mixed models are not yet ruled out by available data sets. In this paper we explore the possibility of obtaining better constraints on the isocurva- ture contribution from future astronomical data. We consider the axion and curvaton inflationary scenarios, and use Planck satellite experimental specifications together with SDSS galaxy survey to forecast for the best parameter error estimation by means of the Fisher information matrix formal- ism. In particular, we consider how CMB lensing information can improve this forecast. We found substantial improvements for all the considered cosmological parameters. In the case of isocurvature amplitude this improvement is strongly model dependent, varying between less than 1% and above 20% around its fiducial value. Furthermore, CMB lensing enables the degeneracy break between the isocurvature amplitude and correlation phase in one of the models. In this sense, CMB lensing information will be crucial in the analysis of future data.