Primordial gravitational wave phenomenology with polarized Sunyaev Zel'dovich tomography

TL;DR

This paper investigates how polarized Sunyaev Zel'dovich (pSZ) tomography can be used to detect and constrain primordial gravitational waves by analyzing their impact on the CMB and the remote quadrupole field, offering a new observational approach.

Contribution

It extends previous work by analyzing the full correlations between the primary CMB and the remote quadrupole field to constrain primordial gravitational waves and tensor sector models.

Findings

Futuristic experiments are needed for competitive exclusion limits.

pSZ tomography can probe late-time tensor evolution.

Cross-correlations can mildly improve constraints on chiral gravitational wave models.

Abstract

The detection and characterization of primordial gravitational waves through their impact on the polarization anisotropies of the cosmic microwave background (CMB) is a primary science goal of current and future observations of the CMB. An ancillary dataset that will become accessible with the great leaps in sensitivity of CMB experiments is the polarized Sunyaev Zel'dovich (pSZ) effect, small-scale CMB polarization anisotropies induced by scattering from free electrons in the post-reionization Universe. The cross correlation of the pSZ effect with galaxy surveys, a technique known as pSZ tomography, can be used to reconstruct the remote quadrupole field: the CMB quadrupole observed from different locations in the Universe. Primordial gravitational waves leave a distinct imprint on the remote quadrupole field, making pSZ tomography a potential new method to characterize their properties. Building on previous work, we explore the utility of the full set of correlations between the primary CMB and the reconstructed remote quadrupole field to both provide exclusion limits on the amplitude of primordial gravitational waves, as well as to provide constraints on several phenomenological models of the tensor sector: axion gauge field inflation, general models with chiral tensors, and models with modified late-time decay of tensors. We find that relatively futuristic experimental requirements are necessary to provide competitive exclusion limits compared with the primary CMB. However, pSZ tomography can be a powerful probe of the late-time evolution of tensors and, through cross-correlations with the primary CMB, can provide mild improvements on parameter constraints in various models with chiral primordial gravitational waves.