Speaker
Description
We investigate cosmology-driven modifications to Schwarzschild-like black hole spacetimes and their impact on photon propagation and gravitational lensing. The effective potential for null geodesics exhibits a single unstable maximum defining the photon sphere, with its radius and stability influenced by the deviation parameter (α) and the angular momentum of the photon (L).Photon trajectories are categorized into capture, escape, and unstable circular paths according to the critical impact parameter (bc). The gravitational deflection angle increases with α, enhancing light bending compared to the standard Schwarzschild case. Weak-field deflection remains largelyunchanged, whereas strong-field regimes exhibit significant deviations. Cosmology-induced modifications introduce potentially observable corrections to light deflection, indicating that forthcoming high-precision astrometric and lensing measurements may provide meaningful constraints. These findings demonstrate the potential to probe modified gravity effects in strong gravitational fields, establishing a connection between astrophysical black holes and cosmology, and offering a pathway to explore how cosmic expansion subtly influences local gravitational phenomena.
