Dynamics of test particles around a Bardeen black hole surrounded by perfect fluid dark matter

TL;DR

This paper investigates how magnetic charge and perfect fluid dark matter influence test particle dynamics around a Bardeen black hole, revealing effects on the ISCO radius and potential degeneracy with black hole spin.

Contribution

It introduces a detailed analysis of test particle orbits around a Bardeen black hole with dark matter, highlighting the impact of magnetic charge and dark matter on ISCO and black hole mimicking effects.

Findings

Magnetic charge and dark matter significantly alter the ISCO radius.

The combined effects can mimic black hole rotation up to a/M≈0.9.

ISCO for magnetic dipole disappears beyond a certain magnetic interaction parameter.

Abstract

We study the dynamics of (i) neutral test particles, (ii) magnetically charged test particles, and (iii) test magnetic dipole around a regular Bardeen black hole surrounded by perfect fluid dark matter (PFDM). It has been shown how the magnetic charge of the black hole and the parameter of the surrounding PFDM can influence the innermost stable circular orbit (ISCO) radius of a test particle. We have found that the ISCO radius is strongly affected as a consequence of the combined effect of the magnetic charge parameter and the perfect fluid dark matter. The black hole magnetic charge parameter $g$ and the combined effect of perfect fluid dark matter can mimic the black hole rotation parameter up to $a/M\approx 0.9$. It has been observed that the ISCO for magnetic dipole disappears at the values exceeding the calculated upper value for the magnetic interaction parameter $\beta$. The upper limit decreases with the increase of both the dark matter and magnetic charge parameters. Finally, as an astrophysical application, we have analyzed degeneracy effects of spin of Kerr black holes and magnetic charge of regular Bardeen black holes for the different values of the dark matter parameter providing exactly the same value for ISCO radius of a magnetic dipole with the same value of the parameter $\beta=10.2$ of the magnetar called PSR J1745-2900 orbiting around supermassive black hole Sagittarius A*.