Accelerated sources in de Sitter spacetime and the insufficiency of retarded fields

TL;DR

This paper investigates the limitations of retarded fields in de Sitter spacetime, revealing that they can be singular or incomplete near creation light cones, and proposes smooth fields involving both retarded and advanced effects.

Contribution

It introduces a method to construct smooth scalar and electromagnetic fields in de Sitter space using both retarded and advanced effects, addressing the insufficiency of purely retarded fields.

Findings

Retarded fields become singular at creation light cones.

Smooth fields involving both retarded and advanced effects can be constructed.

Analysis includes scalar monopoles, electromagnetic monopoles, and dipoles.

Abstract

The scalar and electromagnetic fields produced by the geodesic and uniformly accelerated discrete charges in de Sitter spacetime are constructed by employing the conformal relation between de Sitter and Minkowski space. A special attention is paid to new effects arising in spacetimes which, like de Sitter space, have spacelike conformal infinities. Under the presence of particle and event horizons, purely retarded fields (appropriately defined) become necessarily singular or even cannot be constructed at the "creation light cones" -- future light cones of the "points" at which the sources "enter" the universe. We construct smooth (outside the sources) fields involving both retarded and advanced effects, and analyze the fields in detail in case of (i) scalar monopoles, (ii) electromagnetic monopoles, and (iii) electromagnetic rigid and geodesic dipoles.