Role of electric charge in shaping equilibrium configurations of fluid tori encircling black holes

TL;DR

This paper explores how electric charge influences the equilibrium shapes of fluid tori around black holes by modeling charged perfect fluids in strong gravitational and electromagnetic fields, highlighting differences from uncharged cases.

Contribution

It introduces a simple test model of charged perfect fluid tori in strong fields, contrasting with ideal MHD models, and constructs 3D axisymmetric configurations around Reissner-Nordström black holes.

Findings

Charged tori exhibit distinct equilibrium configurations compared to uncharged ones.

The model demonstrates the impact of electric charge on torus shape and stability.

Comparison with neutral tori highlights electromagnetic effects on fluid structures.

Abstract

Astrophysical fluids may acquire non-zero electrical charge because of strong irradiation or charge separation in a magnetic field. In this case, electromagnetic and gravitational forces may act together and produce new equilibrium configurations, which are different from the uncharged ones. Following our previous studies of charged test particles and uncharged perfect fluid tori encircling compact objects, we introduce here a simple test model of a charged perfect fluid torus in strong gravitational and electromagnetic fields. In contrast to ideal magnetohydrodynamic models, we consider here the opposite limit of negligible conductivity, where the charges are tied completely to the moving matter. This is an extreme limiting case which can provide a useful reference against which to compare subsequent more complicated astrophysically-motivated calculations. To clearly demonstrate the features of our model, we construct three-dimensional axisymmetric charged toroidal configurations around Reissner-Nordstr\"om black holes and compare them with equivalent configurations of electrically neutral tori.