Thermal field theories coupled to curved spacetime

Thermal field theory is an essential tool for comprehending various physical phenomena, including astrophysical objects such as neutron stars and white dwarfs, as well as the early stages of the universe. Nonetheless, the traditional thermal field theory formulated in Minkowski spacetime is not capable of considering the effects originating from the curved spacetime. These effects are crucial for both astrophysical and cosmological observations, making it essential to extend the domain of thermal field theory to curved spacetimes. This article's primary focus is to explore the extension of thermal field theory to curved spacetimes and its implications. We employ Riemann-normal coordinates to describe thermal field theories in curved spacetime, and we also calculate several thermodynamic observables to demonstrate the curvature corrections explicitly.