Gravito-electromagnetic resonances

TL;DR

This paper investigates gravito-electromagnetic resonances in weak gravitational fields, analyzing how gravitational waves can induce electromagnetic signals and exploring conditions leading to resonance amplification.

Contribution

It provides a covariant analysis of Weyl-Maxwell coupling on Minkowski space and extends the study to cosmological settings, highlighting resonance phenomena and their physical implications.

Findings

Electromagnetic signals can resonate and diverge under certain initial conditions.

Resonance behavior varies between Minkowski space and cosmological environments.

The amplitude of induced electromagnetic waves depends on initial data and gravitational wave properties.

Abstract

The interaction between gravitational and electromagnetic radiation has a rather long research history. It is well known, in particular, that gravity-wave distortions can drive propagating electromagnetic signals. Since forced oscillations provide the natural stage for resonances to occur, gravito-electromagnetic resonances have been investigated as a means of more efficient gravity-wave detection methods. In this report, we consider the coupling between the Weyl and the Maxwell fields on a Minkowski background, which also applies to astrophysical environments where gravity is weak, at the second perturbative level. We use covariant methods that describe gravitational waves via the transverse component of the shear, instead of pure-tensor metric perturbations. The aim is to calculate the properties of the electromagnetic signal, which emerges from the interaction of its linear counterpart with an incoming gravitational wave. Our analysis shows how the wavelength and the amplitude of the gravitationally driven electromagnetic wave vary with the initial conditions. More specifically, for certain initial data, the amplitude of the induced electromagnetic signal is found to diverge. Analogous, diverging, gravito-electromagnetic resonances were also reported in cosmology. Given that, we extend our Minkowski-space study to cosmology and discuss analogies and differences in the physics and in the phenomenology of the Weyl-Maxwell coupling between the aforementioned two physical environments.