Status of CMB observations in 2015

TL;DR

This paper reviews the status of cosmic microwave background observations as of 2015, highlighting key achievements and future challenges in understanding the early universe through CMB data.

Contribution

It provides a comprehensive overview of the observational progress and outlines upcoming challenges in CMB research as of 2015.

Findings

Summary of current CMB observational status in 2015

Discussion of challenges like B modes and gravitational lensing

Emphasis on spectral distortions for probing new physics

Abstract

The 2.725 K cosmic microwave background has played a key role in the development of modern cosmology by providing a solid observational foundation for constraining possible theories of what happened at very large redshifts and theoretical speculation reaching back almost to the would-be big bang initial singularity. After recounting some of the lesser known history of this area, I summarize the current observational situation and also discuss some exciting challenges that lie ahead: the search for B modes, the precision mapping of the CMB gravitational lensing potential, and the ultra-precise characterization of the CMB frequency spectrum, which would allow the exploitation of spectral distortions to probe new physics.