Equatorial light bending around a Hairy Kiselev Black Hole

TL;DR

This paper analyzes how scalar fields and exotic matter influence light bending around a Hairy Kiselev black hole, providing an analytic expression for the deflection angle and comparing effects with other black hole models.

Contribution

It offers the first analytic expression for light deflection in a Hairy Kiselev black hole and explores the scalar field's complex impact on gravitational lensing.

Findings

Deflection angle decreases with impact parameter, aligning with classical lensing.

Scalar coupling initially enhances, then suppresses light bending in strong fields.

Presence of quintessential field increases deflection, scalar hair reduces it.

Abstract

We investigate the deflection angle of light rays confined to the equatorial plane of a Hairy Kiselev black hole. The analysis includes a thorough study of the horizon structure and critical parameters, leading to an analytic expression for the deflection angle in terms of elliptic integrals. Our results confirm that the deflection angle decreases with increasing impact parameter, in agreement with classical predictions of gravitational lensing. The influence of the scalar field, characterized by the coupling constant, shows a nontrivial effect: while moderate values of the coupling constant initially enhance light bending, further increases lead to a suppression of the deflection in the strong-field regime due to modifications in spacetime geometry. Comparative analysis among the Schwarzschild, Kiselev, and Hairy Kiselev black holes indicates that the presence of a quintessential field tends to enhance the deflection, whereas the scalar hair component reduces it. These findings underscore the significant role of scalar fields and exotic matter distributions in shaping light propagation in a modified gravity scenario.