Non-Keplerian Charged Accretion Disk Orbiting a Black Hole~Pulsar

TL;DR

This paper models the equilibrium structures of charged, non-conducting fluids in non-Keplerian accretion disks around Kerr black holes influenced by magnetic dipoles, revealing complex interactions affecting disk properties.

Contribution

It introduces a novel analysis of charged perfect fluids orbiting Kerr black holes under magnetic dipole influence, highlighting non-Keplerian dynamics and equilibrium configurations.

Findings

Charged fluid disks exhibit non-Keplerian angular momentum profiles.

Magnetic dipole effects significantly alter disk geometry and density.

The model predicts specific equilibrium structures influenced by charge and magnetic fields.

Abstract

Recent studies have focused on how spinning black holes (BHs) within a binary system containing a strongly magnetized neutron star, then immersed in external magnetic fields, can acquire charge through mechanisms like the Wald process and how this charge could power pulsar-like electromagnetic radiation. Those objects called ``Black hole pulsar'' mimic the behaviour of a traditional pulsar, and they can generate electromagnetic fields, such as magnetic dipoles. Charged particles within an accretion disk around the black hole would then be influenced not only by the gravitational forces but also by electromagnetic forces, leading to different geometries and dynamics. In this context, we focus here on the interplay of the magnetic dipole and the accretion disk. We construct the equilibrium structures of non-conducting charged perfect fluids orbiting Kerr black holes under the influence of a dipole magnetic field aligned with the rotation axis of the BH. The dynamics of the accretion disk in such a system are shaped by a complex interplay between the non-uniform, non-Keplerian angular momentum distribution, the black hole's induced magnetic dipole, and the fluid's charge. We show how these factors jointly influence key properties of the disk, such as its geometry, aspect ratio, size, and rest mass density.