Perspectives on gravity-induced radiative processes in astrophysics

TL;DR

This paper develops a comprehensive method to calculate gravitationally induced radiative processes for particles of any spin in arbitrary metrics, revealing how small dissipation can cause resonances and back-reaction effects.

Contribution

It introduces procedures for calculating lowest order diagrams and transition probabilities for particles in gravitational fields, including all orders in metric deviation and effects of dissipation.

Findings

Single-vertex diagrams can be relevant in gravitational backgrounds due to effective mass.

Dissipation can trigger resonances and back-reaction in radiative processes.

The methods apply to particles of any spin in arbitrary gravitational metrics.

Abstract

Single-vertex Feynman diagrams represent the dominant contribution to physical processes, but are frequently forbidden kinematically. This is changed when the particles involved propagate in a gravitational background and acquire an effective mass. Procedures are introduced that allow the calculation of lowest order diagrams, their corresponding transition probabilities, emission powers and spectra to all orders in the metric deviation, for particles of any spin propagating in gravitational fields described by any metric. Physical properties of the "space-time medium" are also discussed. It is shown in particular that a small dissipation term in the particle wave equations can trigger a strong back-reaction that introduces resonances in the radiative process and affects the resulting gravitational background.