CMB Lensing Constraints on Neutrinos and Dark Energy

TL;DR

This paper evaluates how future CMB experiments can constrain neutrino masses and dark energy properties by analyzing lensing effects, comparing methods, and considering systematics.

Contribution

It provides forecasts for neutrino and dark energy constraints from upcoming CMB experiments, including polarization and lensing potential analyses, with a simple method for combining with supernova data.

Findings

Realistic CMBpol can constrain neutrino mass sum to 0.05 eV.

CMBpol can measure early dark energy fraction to 0.002.

Optimal quadratic estimators improve lensing measurements.

Abstract

Signatures of lensing of the cosmic microwave background radiation by gravitational potentials along the line of sight carry with them information on the matter distribution, neutrino masses, and dark energy properties. We examine the constraints that Planck, PolarBear, and CMBpol future data, including from the B-mode polarization or the lensing potential, will be able to place on these quantities. We simultaneously fit for neutrino mass and dark energy equation of state including time variation and early dark energy density, and compare the use of polarization power spectra with an optimal quadratic estimator of the lensing. Results are given as a function of systematics level from residual foreground contamination. A realistic CMBpol experiment can effectively constrain the sum of neutrino masses to within 0.05 eV and the fraction of early dark energy to 0.002. We also present a surprisingly simple prescription for calculating dark energy equation of state constraints in combination with supernova distances from JDEM.