# Magnetized Black Holes: Interplay between Charge and Rotation

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## Abstract

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## 1. Introduction

## 2. Magnetized Kerr–Newman Black Hole in Charge Equilibrium

## 3. Weak Magnetic Field and Particle Acceleration

## 4. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**Surface plot of the magnetic flux function, $F(a,e)$, across a hemisphere bounded by $\theta =\pi /2$ and located on the MKN black hole horizon. A fixed value of the magnetization parameter $\beta =0.05$ has been selected. Projected contours are also shown for improved clarity of the plot. The surface is restricted by the condition for the emergence of the event horizon, ${a}^{2}+{e}^{2}\le 1$. Four circles of $\sqrt{(}{a}^{2}+{e}^{2})=0.25$, 0.5, 0.75, and 1.0 are shown to guide the eye. The yellow band on the surface, denoted by “Z”, indicates where the total electric charge is zero. Note: Unlike the case of a weakly magnetized black hole, the moment of vanishing charge does not coincide with zero of the charge parameter, $e=0$. On the other hand, $Q(a,e=0)$ does not vanish and its graph is shown by a solid curve “Q”. This is the feature of the exact MKN metric, where the two nulls do not generally coincide, as further detailed in [17] (this figure has been reproduced with permission from Physica Scripta article ref. [18]).

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**MDPI and ACS Style**

Karas, V.; Stuchlík, Z.
Magnetized Black Holes: Interplay between Charge and Rotation. *Universe* **2023**, *9*, 267.
https://doi.org/10.3390/universe9060267

**AMA Style**

Karas V, Stuchlík Z.
Magnetized Black Holes: Interplay between Charge and Rotation. *Universe*. 2023; 9(6):267.
https://doi.org/10.3390/universe9060267

**Chicago/Turabian Style**

Karas, Vladimír, and Zdeněk Stuchlík.
2023. "Magnetized Black Holes: Interplay between Charge and Rotation" *Universe* 9, no. 6: 267.
https://doi.org/10.3390/universe9060267