Covariant Evolution of Gravitoelectromagnetism

TL;DR

This paper reviews the covariant formalism of gravitoelectromagnetism, analyzing the dynamical equations of the Weyl tensor's electric and magnetic parts, and discusses their implications for gravitational wave propagation and observational effects.

Contribution

It provides a detailed analysis of the dynamical and kinematic equations governing gravitoelectric and gravitomagnetic fields using covariant formalisms, including new insights into gravitational wave propagation and multi-fluid models.

Findings

Conditions for gravitational wave propagation are identified.

Newtonian models without gravitomagnetism are shown to be inconsistent.

Observational effects of Weyl fields on kinematic quantities are discussed.

Abstract

The long-range gravitational terms associated with tidal forces, frame-dragging effects, and gravitational waves are described by the Weyl conformal tensor, the traceless part of the Riemann curvature that is not locally affected by the matter field. The Ricci and Bianchi identities provide a set of dynamical and kinematic equations governing the matter coupling and evolution of the electric and magnetic parts of the Weyl tensor, so-called gravitoelectric and gravitomagnetic fields. A detailed analysis of the Weyl gravitoelectromagnetic fields can be conducted using a number of algebraic and differential identities prescribed by the 1+3 covariant formalism. In this review, we consider the dynamical constraints and propagation equations of the gravitoelectric/-magnetic fields and covariantly debate their analytic properties. We discuss the special conditions under which gravitational waves can propagate, the inconsistency of a Newtonian-like model without gravitomagnetism, the nonlinear generalization to multi-fluid models with different matter species, as well as observational effects caused by the Weyl fields via the kinematic quantities. The 1+3 tetrad and 1+1+2 semi-covariant methods, which can equally be used for gravitoelectromagnetism, are briefly explained, along with their correspondence with the covariant formulations.