paper

Lensing Stability and Scattering Phenomena in Anisotropic Black Hole Spacetimes in Plasma

arXiv:2508.21519 · doi:10.1088/1475-7516/2025/12/023

Abstract

We investigate the physical and observational features of static, spherically symmetric black hole spacetimes surrounded by anisotropic fluid and embedded in a plasma environment. Motivated by recent advances in black hole imaging and precision measurements in strong gravity, we explore light propagation, wave dynamics, and observational signatures in such geometries. We begin by analyzing the background spacetime and matter content, examining the horizon structure and verifying the energy conditions associated with the anisotropic fluid. We then study photon trajectories in both vacuum and plasma environments, deriving the equations of motion and computing deflection angles and image magnifications under weak gravitational lensing. Both uniform and power-law plasma profiles are considered to model realistic astrophysical settings. In the wave optics regime, we first analyze the linear stability of the spacetime under axial (odd-parity) perturbations using Chandrasekhar's method, and then investigate scalar field scattering by solving the wave equation in the curved background with plasma. Using Born and WKB approximations, we compute the differential scattering cross-sections and examine how anisotropy and plasma affect interference features. Finally, we perform parameter estimation using Markov Chain Monte Carlo methods to constrain the black hole mass and anisotropic fluid parameters, utilizing EHT and GRAVITY data for Sgr A* and EHT-only data for M87*. These results present a unified theoretical framework that links anisotropic matter effects with lensing and scattering observables providing a firm basis for future comparisons with high-resolution astrophysical data sets in diverse contexts.

Updated to match the published version; results remain unchanged

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