Effect of radiation flux on test particle motion in the Vaidya spacetime

TL;DR

This paper examines how radiation flux influences the movement of test particles in the Vaidya spacetime, highlighting equilibrium positions and comparing with Schwarzschild results, using a Poynting-Robertson-like effect model.

Contribution

It introduces a detailed analysis of test particle dynamics in Vaidya spacetime considering radiation interaction, extending previous Schwarzschild studies with new equilibrium insights.

Findings

Existence of equilibrium positions for particles in Vaidya spacetime

Comparison of particle motion with Schwarzschild background results

Modeling of radiation drag force similar to Poynting-Robertson effect

Abstract

Motion of massive test particles in the nonvacuum spherically symmetric radiating Vaidya spacetime is investigated, allowing for physical interaction of the particles with the radiation field in terms of which the source energy-momentum tensor is interpreted. This "Poynting-Robertson-like effect" is modeled by the usual effective term describing a Thomson-type radiation drag force. The equations of motion are studied for simple types of motion including free motion (without interaction), purely radial and purely azimuthal (circular) motion, and for the particular case of "static" equilibrium; appropriate solutions are given where possible. The results---mainly those on the possible existence of equilibrium positions---are compared with their counterparts obtained previously for a test spherically symmetric radiation field in a vacuum Schwarzschild background.