Shadows and rings of the Kehagias-Sfetsos black hole surrounded by thin disk accretion

TL;DR

This study investigates the shadows and rings of Kehagias-Sfetsos black holes in deformed Hořava-Lifshitz gravity using ray-tracing, revealing how the HL parameter influences observable features and potential distinctions from Schwarzschild black holes.

Contribution

It provides a detailed analysis of black hole shadows and rings in HL gravity, highlighting the effects of the HL parameter on observable features and their potential to differentiate from Schwarzschild black holes.

Findings

Photon sphere radius decreases with HL parameter 

Direct emission dominates observed intensity

Lensing and photon rings contribute minimally

Abstract

In this paper, under the illumination of thin disk accretion, we have employed the ray-tracing method to carefully investigate shadows and rings of the Kehagias-Sfetsos(KS) black hole in deformed Ho\v{r}ava-Lifshitz(HL) gravity. The results show that the event horizon $r_+$, the radius $r_p$ and impact parameter $b_{p}$ of photon sphere are all decreased with the increase of the HL parameter $\omega$, but the effective potential increases. And, it also turns out that the trajectories of light rays emitted from the north pole direction are defined as the direct emission, lensing ring and photon ring of KS black hole, on the basis of orbits $n = \phi/2\pi$. As black hole surrounded by thin disk accretion, we show that the corresponding transfer functions have their values increased with the parameter $\omega$. More importantly, we also find that the direct emissions always dominate the total observed intensity, while lensing rings as a thin ring make a very small contribution and photon ring as a extremely narrow ring make a negligible contribution, for all three toy-model functions. In view of this, the results finally imply that shadows and rings as the observational appearance of KS black hole exhibit some obvious interesting features, which might be regarded as an effective way to distinguish black holes in HL gravity from the Schwarzschild black hole.