Weak gravitational lensing by an ESTGB black hole in the presence of a plasma

TL;DR

This study investigates how a plasma medium and magnetic charges influence weak gravitational lensing by a 4D ESTGB black hole, revealing that plasma distribution significantly affects light deflection and magnification.

Contribution

It provides a detailed analysis of plasma effects on gravitational lensing around a 4D ESTGB black hole, including the impact of magnetic charges and different plasma models.

Findings

Uniform plasma increases light deflection more than SIS and NSIS models.

Magnetic charge magnitude slightly affects deflection angle.

Uniform plasma enhances total magnification, non-uniform reduces it.

Abstract

This paper is devoted to studying the weak-field gravitational lensing properties of a 4D ESTGB black hole, which is surrounded by the plasma medium. The effects of the magnetic charges and the three plasma distribution models in the deflection of light around a 4D ESTGB black hole are investigated in detail. We find that the uniform plasma leads to a larger deflection of light rays in comparison with the singular isothermal sphere (SIS), the non-singular isothermal sphere (NSIS) models. Moreover, the deflection angle increases slightly as the absolute value of the magnetic charge decreases. Finally, we analyze the total magnification of image due to weak gravitational lensing around the black hole. The result shows that the presence of a uniform plasma medium remarkably enhances the total magnification whereas the non-uniform plasma reduces the total magnification.