Rotating Black Hole Shadow in Perfect Fluid Dark Matter

TL;DR

This paper analytically examines how a rotating black hole's shadow is affected by perfect fluid dark matter, revealing dependencies on spin and dark matter intensity, with implications for future astronomical observations.

Contribution

It provides an analytical study of black hole shadows in perfect fluid dark matter, highlighting the effects of spin and dark matter parameters on shadow shape and size.

Findings

Shadow shape varies with spin and dark matter intensity.

Size and distortion of shadow depend on the parameter k and a.

Energy emission rate increases with dark matter intensity.

Abstract

We study analytically the shadow cast by the rotating black hole in the perfect fluid dark matter. The apparent shape of the shadow depends upon the black hole spin $a$ and the perfect fluid dark matter intensity parameter $k$ ($k>0$). In general, the shadow is a perfect circle in the non-rotating case ($a=0$) and a deformed one in the rotating case ($a\neq 0$). The deformation gets more and more significant with the increasing $a$, similar to the Schwarzschild and Kerr black holes. In addition, there exists a reflection point $k_0$. When $k<k_0$, the size of the shadow decreases with the increasing $k$ and the distortion increases with the increasing $k$. When $k>k_0$, the size of the shadow increases with the increasing $k$ and the distortion decreases with the increasing $k$. Furthermore, the energy emission rate of the black hole in the perfect fluid dark matter increases with the increasing $k$ and the peak of the emission shifts to higher frequencies. Finally, we propose that to observe the effect of the black hole spin $a$ and the perfect fluid dark matter intensity $k$ on the shadow of the black hole Sgr A$^{*}$ at the center of the Milky Way, highly improved techniques would be necessary for the development of future astronomical instruments.