Electromagnetic waves around dilatonic stars and naked singularities

TL;DR

This paper investigates how electromagnetic waves propagate around dilatonic stars and naked singularities, analyzing energy loss and radiation effects caused by the dilaton field using perturbative and numerical methods.

Contribution

It provides a perturbative analysis of electromagnetic wave behavior in dilaton backgrounds, revealing effects on luminosity and radiation not previously detailed.

Findings

Energy loss due to back-scattering against the dilaton field.

Altered luminosity profiles of stars with dilaton fields.

Radiation characteristics of sources near dilatonic backgrounds.

Abstract

We study the propagation of classical electromagnetic waves on the simplest four-dimensional spherically symmetric metric with a dilaton background field. Solutions to the relevant equations are obtained perturbatively in a parameter which measures the strength of the dilaton field (hence parameterizes the departure from Schwarzschild geometry). The loss of energy from outgoing modes is estimated as a back-scattering process against the dilaton background, which would affect the luminosity of stars with a dilaton field. The radiation emitted by a freely falling point-like source on such a background is also studied by analytical and numerical methods.