By Dawn's Early Light: CMB Polarization Impact on Cosmological Constraints

TL;DR

This paper discusses how CMB polarization data from various ground-based and satellite surveys enhances constraints on dark energy, neutrino mass, and gravity, significantly improving cosmological parameter estimates and reshaping the dark energy research landscape.

Contribution

It evaluates the impact of current and future CMB polarization measurements on cosmological constraints, highlighting the improvements from ground-based surveys and additional low-redshift observations.

Findings

Ground-based CMB surveys strengthen dark energy and neutrino mass constraints by factors of 3-4.

Adding strong lensing time delay data improves dark energy constraints by 32%.

Enhanced low redshift supernova surveys improve constraints by 26%.

Abstract

Cosmic microwave background polarization encodes information not only on the early universe but also dark energy, neutrino mass, and gravity in the late universe through CMB lensing. Ground based surveys such as ACTpol, PolarBear, SPTpol significantly complement cosmological constraints from the Planck satellite, strengthening the CMB dark energy figure of merit and neutrino mass constraints by factors of 3-4. This changes the dark energy probe landscape. We evaluate the state of knowledge in 2017 from ongoing experiments including dark energy surveys (supernovae, weak lensing, galaxy clustering), fitting for dynamical dark energy, neutrino mass, and a modified gravitational growth index. Adding a modest strong lensing time delay survey improves those dark energy constraints by a further 32%, and an enhanced low redshift supernova program improves them by 26%.