Shadow of a rotating squashed Kaluza-Klein black hole

Fen Long,Jieci Wang,Jiliang Jing,Songbai Chen

doi:10.1007/jhep10(2019)269

Fen Long, Jieci Wang + Show 2 more

Open Access

https://doi.org/10.1007/jhep10(2019)269

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Abstract

We study the shadow of a rotating squashed Kaluza-Klein (KK) black hole and the shadow is found to possess distinct properties from those of usual rotating black holes. It is shown that the shadow for a rotating squashed KK black hole is heavily influenced by the specific angular momentum of photon from the fifth dimension. Especially, as the parameters lie in a certain special range, there is no any shadow for a black hole, which does not emerge for the usual black holes. In the case where the black hole shadow exists, the shadow shape is a perfect black disk and its radius decreases with the rotation parameter of the black hole. Moreover, the change of the shadow radius with extra dimension parameter also depends on the rotation parameter of black hole. Finally, with the latest observation data, we estimate the angular radius of the shadow for the supermassive black hole Sgr A∗ at the centre of the Milky Way galaxy and the supermassive black hole in M 87.

Highlights

JHEP10(2019)[269] holes, the size of compactified extra dimension can be adjusted by the parameter r∞
We find that the θ-component equation is independent of the rotation parameter and it is exactly identical to the equation in the static squashed KK black hole spacetime, which would yield some special properties of the shadow of the black hole (2.20)
The circular silhouette of the shadow for the rotating squashed KK black hole is caused by the spacetime property that there are two equal rotational parameters in this special black hole spacetime, which leads to that the θ-component equation is independent of the rotation parameter

Summary

Introduction

JHEP10(2019)[269] holes, the size of compactified extra dimension can be adjusted by the parameter r∞. It is shown that the shadow for a rotating squashed KK black hole is heavily influenced by the specific angular momentum of photon from the fifth dimension.

Results

Conclusion