The Cosmic Microwave Background -- Secondary Anisotropies

TL;DR

This paper reviews secondary anisotropies in the cosmic microwave background, exploring their physical origins, observational status, and potential to enhance our understanding of the Universe's fundamental properties and evolution.

Contribution

It provides a comprehensive overview of the mechanisms, current observations, and future prospects of secondary CMB anisotropies in cosmology.

Findings

Secondary anisotropies encode information about large-scale structure.

Observations are increasingly sensitive, enabling new insights.

Synergy with LSS surveys enhances cosmological constraints.

Abstract

The cosmic microwave background (CMB), the relic radiation from the early Universe, offers a unique window into both primordial conditions and the intervening large-scale structure (LSS) it traverses. Interactions between CMB photons and the evolving Universe imprint secondary anisotropies -- modifications to the CMB's intensity and polarization caused by gravitational effects and scattering processes. These anisotropies serve as a powerful probe of fundamental physics while also revealing astrophysical processes governing the thermodynamics and distribution of baryonic matter. In this chapter, we provide a comprehensive review of the physical mechanisms underlying secondary anisotropies, their observational status, and their potential to advance precision cosmology. With the increasing sensitivity of CMB experiments and synergy with LSS surveys, secondary anisotropies are poised to unveil unprecedented insights into the Universe's composition, evolution, and dynamics.