Synchrotron emitting Komissarov torus with magnetic polarization around Kerr black holes

TL;DR

This study uses numerical simulations to explore how magnetic polarization affects the observable properties of synchrotron-emitting accretion disks around Kerr black holes, revealing effects dependent on plasma pressure and magnetic susceptibility.

Contribution

It systematically analyzes the impact of magnetic polarization on accretion disk emission and morphology around Kerr black holes using numerical simulations, highlighting the role of magnetic susceptibility.

Findings

Magnetic polarization effects are negligible in gas pressure-dominated disks.

Emission intensity increases as beta-plasma decreases in magnetic pressure-dominated disks.

Paramagnetic disks emit the highest flux regardless of beta-plasma.

Abstract

Magnetic fields in black hole accretion disks are associated with processes of mass accretion and energy amplification. The contribution of the magnetic field due to the magnetic polarization of the material induces effects on the physical properties of the medium that have repercussions on the radiation coming from the accretion disks. Hence, from observations, it could be possible to infer the "fingerprint" left by the magnetic polarization of the material and establish the properties of the spacetime itself. As the first step in this purpose, we use numerical simulations to systematically analyze the possible observable effects produced by the magnetic properties of an accretion disk around a Kerr black hole. We found that under the synchrotron radiation power-law model the effects of the magnetic polarization are negligible when the plasma is gas pressure-dominated. Nevertheless, as beta-plasma decreases, the emission becomes more intense for magnetic pressure-dominated disks. In particular, we found that paramagnetic disks emit the highest intensity value independent of the beta-plasma parameter in this regime. By contrast, the emitted flux decreases with the increase of beta-plasma due to the dependence of the magnetic field on the emission and absorption coefficients. Moreover, the disk morphology changes with the magnetic susceptibility: paramagnetic disks are more compact than diamagnetic ones. This fact leads to diamagnetic disks emitting a greater flux because each photon has a more optical path to travel inside the disk.