CMB Spectral Distortions: A Multimessenger Probe of the Primordial Universe

TL;DR

This paper reviews how future measurements of CMB spectral distortions, combined with gravitational wave and 21cm observations, can provide new insights into the primordial universe and distinguish between exotic physics models.

Contribution

It highlights the potential of multimessenger approaches involving spectral distortions, gravitational waves, and 21cm cosmology to probe the early universe and discriminate between theoretical models.

Findings

Spectral distortions encode information about the primordial universe.

Synergies between different observational probes enhance model discrimination.

Future experiments can significantly improve understanding of exotic physics scenarios.

Abstract

The frequency spectrum of the cosmic microwave background (CMB) is a relatively untapped source of data which can allow us to peer beyond the surface of last scattering. Small deviations away from a perfect blackbody shape will encode valuable information about the state of the primordial Universe which may not be accessible by other means. Here, we briefly review some key science goals of CMB spectral distortions, with an emphasis on how future generations of experiments can be used in tandem with complementary observational probes to perform model discrimination of exotic physics scenarios. We focus here on synergies between spectral distortions, gravitational waves, and 21cm cosmology.