Future Steps in Cosmology using Spectral Distortions of the Cosmic Microwave Background

Understand

Since the measurements of COBE/FIRAS in the mid-90's we know that the energy spectrum of the cosmic microwave background (CMB) is extremely close to that of a perfect blackbody at an average temperature T0~2.726K.

• However, a number of early-universe processes are expected to create CMB spectral distortions - departures of the average CMB energy spectrum from a blackbody - at a level that is within reach of present-day technology.
• This provides strong motivation to study the physics of CMB spectral distortions and ask what these small signals might be able to tell us about the Universe we live in.
• In this lecture, I will give a broad-brush overview of recent theoretical and experimental developments, explaining why future spectroscopic measurements of the CMB will open an unexplored new window to early-universe and particle physics.