Greybody factors for non-minimally coupled scalar fields in Schwarzschild-de Sitter spacetime

TL;DR

This paper analyzes how non-minimal coupling affects greybody factors and Hawking radiation of scalar fields in Schwarzschild-de Sitter spacetime, revealing that coupling influences low-frequency behavior and absorption characteristics.

Contribution

It provides the first detailed calculation of greybody factors for non-minimally coupled scalar fields in Schwarzschild-de Sitter spacetime, highlighting differences from minimal coupling.

Findings

Zero-angular-momentum greybody factor tends to zero as frequency squared with non-zero coupling.

In contrast to minimal coupling, the greybody factor approaches zero at low frequencies.

A generalized absorption cross section is formulated and analyzed.

Abstract

We compute the greybody factors for non-minimally coupled scalar fields in four-dimensional Schwarzschild-de Sitter spacetime. In particular, we demonstrate that the zero-angular-momentum greybody factor generically tends to zero in the zero-frequency limit like frequency squared if there is non-vanishing coupling to the scalar curvature. This is in contrast with the minimally coupled case, where the greybody factor is known to tend to a finite constant. We also study the Hawking radiation for non-minimally coupled massless scalar fields in Schwarzschild-de Sitter spacetime, formulate a sensible notion of a generalized absorption cross section and investigate its properties.