The synergy between CMB spectral distortions and anisotropies

TL;DR

This paper explores how spectral distortions and anisotropies of the CMB can jointly enhance our understanding of early universe energy injections, emphasizing the potential of future spectral distortion measurements to surpass traditional probes.

Contribution

It introduces a unified framework within the Boltzmann code CLASS for analyzing spectral distortions alongside anisotropies, and discusses their combined potential for cosmological and particle physics insights.

Findings

Spectral distortions can provide constraints surpassing traditional probes.

A unified computational framework for thermal evolution of photons and baryons.

Spectral distortions offer a novel, complementary probe for early universe energy processes.

Abstract

Spectral distortions and anisotropies of the CMB provide independent and complementary probes to study energy injection processes in the early universe. Here we discuss the synergy between these observables, and show the promising future of spectral distortion missions to constrain both exotic and non-exotic energy injections. We show that conventional probes such as Big Bang Nucleosynthesis and CMB anisotropies can benefit from and even be surpassed by future spectral distortion experiments. For this, we have implemented a unified framework within the Boltzmann code CLASS to consistently treat the thermal evolution of photons and baryons. Furthermore, we give an extensive and pedagogical introduction into the topic of spectral distortions and energy injections throughout the thermal history of the universe, highlighting some of their unique features and potential as a novel probe for cosmology and particle physics.