Cosmological gravitational particle production and its implications for cosmological relics

TL;DR

This paper reviews how particles created by gravitational effects in an expanding universe influence cosmological relics like dark matter and gravitational waves, highlighting their spectra, abundance, and observational signatures.

Contribution

It provides a comprehensive overview of cosmological gravitational particle production, detailing its mechanisms, known results, and implications for cosmology.

Findings

Spectra and abundance of gravitationally produced particles are cataloged.

Implications for dark matter, gravitational waves, and baryon asymmetry are discussed.

Potential observational signatures of CGPP are explored.

Abstract

Cosmological gravitational particle production (CGPP) is the creation of particles in an expanding universe due solely to their gravitational interaction. These particles can play an important role in the cosmic history through their connection to various cosmological relics including dark matter, gravitational wave radiation, dark radiation, and the baryon asymmetry. This review explains the phenomenon of CGPP as a consequence of quantum fields in a time-dependent background, catalogs known results for the spectra and cosmological abundance of gravitationally produced particles of various spins, and explores the phenomenological consequences and observational signatures of CGPP.