# Electromagnetic emissions from near-horizon region of an extreme Kerr-Taub-Nut black hole

## TL;DR

This study investigates how the NUT charge influences electromagnetic line emissions near the horizon of an extremal Kerr-Taub-NUT black hole, revealing brightness variations and redshift effects depending on observer position.

## Contribution

It provides the first analysis of electromagnetic emissions in Kerr-Taub-NUT spacetime, highlighting the impact of NUT charge and observer location on emission characteristics.

## Key findings

- Electromagnetic emissions are brighter in Kerr-Taub-NUT than Kerr black holes for equatorial and Southern Hemisphere observers.
- Emission brightness decreases as the observer moves away from the equatorial plane in the Northern Hemisphere.
- Redshift effects significantly influence the observed electromagnetic emissions near the black hole horizon.

## Abstract

We have studied electromagnetic line emissions from near-horizon region in the extremal Kerr-Taub-NUT black hole spacetime and then probe the effects of NUT charge on the electromagnetic line emissions. Due to the presence of the NUT charge, the equatorial plane is no more a symmetry plane of the KTN spacetime, which leads to that the dependence of electromagnetic line emission on the NUT charge for the observer in the Southern Hemisphere differs from that in the Northern one. Our result indicate that the electromagnetic line emission in the Kerr-Taub-NUT black hole case is brighter than that in the case of Kerr black hole for the observer in the equatorial plane or in the Southern Hemisphere, but it becomes more faint as the observer's position deviates far from the equatorial plane in the Northern one. Moreover, we also probe effects of redshift factor on electromagnetic emission from near-horizon region in the extremal Kerr-Taub-NUT black hole spacetime.