Gravitational lensing around a Kerr-Sen black hole in plasma background

TL;DR

This paper studies how plasma affects gravitational lensing around a Kerr-Sen black hole, analyzing light deflection, photon orbits, and comparing plasma and vacuum scenarios to enhance understanding of observational signatures.

Contribution

It introduces a detailed analysis of plasma effects on light bending around a Kerr-Sen black hole, considering both homogeneous and inhomogeneous plasma environments.

Findings

Plasma modifies the light deflection angle compared to vacuum.

Rotation and charge of the black hole influence photon orbits.

Plasma effects can significantly alter observational signatures of black holes.

Abstract

We investigate the gravitational lensing of massless particles around a Kerr-Sen black hole immersed in a magnetized, cold, pressureless plasma medium. Both homogeneous and inhomogeneous plasma distributions are considered in this study to mimic realistic astrophysical environments. The light deflection angle is computed, and the effects of the black hole's rotation and charge on light bending are analyzed in detail. The conditions for the circular photon orbits are also examined in both plasma configurations. A comparison with the vacuum case (i.e. zero plasma frequency) highlights the role of plasma in modifying the light propagation, and the results obtained provide a deeper insight into plasma effects which improve our understanding of observational signatures of rotating charged black holes.