Radiation from an emitter revolving around a magnetized non-rotating black hole

TL;DR

This paper investigates how magnetic fields near non-rotating black holes affect the spectral broadening of emission lines from orbiting ions, aiming to use spectral profiles to infer magnetic field properties.

Contribution

It introduces a study of the impact of magnetic fields on ion motion and spectral line broadening around non-rotating black holes, which is a novel approach.

Findings

Magnetic fields cause ions' stable orbits to move closer to the black hole horizon.

Spectrum broadening profiles are sensitive to magnetic field strength.

Potential to use spectral observations to estimate magnetic fields near black holes.

Abstract

One of the methods of study of black holes in astrophysics is based on broadening of the spectrum of radiation of ionized Iron atoms. The line K$\alpha$ associated with Iron emission at 6.4 keV is very narrow. If such an ion is revolving around a black hole, this line is effectively broadened as a result of the Doppler and gravitational redshift effects. The profile of the broaden spectrum contains information about the gravitational field of the black hole. In the presence of a regular magnetic field in the vicinity of a black holes the characteristics of the motion of charged ions are modified. In particular, their innermost stable circular orbits become closer to the horizon. The purpose of this work is to study how this effect modifies the spectrum broadening of lines emitted by such an ion. Our final goal is to analyze whether the change of the spectrum profiles can give us information about the magnetic field in the black hole vicinity.