Strong gravitational lensing around Kehagias-Sfetsos compact objects surrounded by plasma

TL;DR

This paper investigates how Hořava gravity and plasma affect strong gravitational lensing around Kehagias-Sfetsos black holes, providing semi-analytical calculations relevant for supermassive black holes like M87.

Contribution

It introduces a semi-analytical method to analyze the influence of Hořava gravity and plasma on strong lensing phenomena around KS black holes, including image separation and magnification.

Findings

Image magnification sensitivity to parameters is 1-10%.

Image separation sensitivity is around 16%.

Shadow size varies with KS and plasma parameters.

Abstract

We present the analysis how Ho\v{r}ava gravity and plasma influence the strong lensing phenomena around Kehagias-Sfetsos (KS) black holes. Using the semi-analytical Bozza method of strong lensing limit, we determine the multiple images, namely their separation S, and magnification R. We apply our calculations to the case of supermassive black hole having mass $M=6.5\times 10^{9}\textrm{M}_\odot$ and being at distance $d_0=16.8\textrm{Mpc}$ from observer corresponding to those observed in M87. We show that the sensitivity of image magnification, image separation, and shadow angular size on KS parameter $\omega$ and plasma parameter $k$ are of order from $1\%$ to $10\%$ for $R$ and $~\,16\%$ for $S$.