Shadows for Kerr–Sen–Taub–NUT black holes with Manko–Ruiz parameter

Abstract

In this paper, we explore the Kerr–Sen–Taub–NUT spacetime with the inclusion of the Manko–Ruiz parameter. We demonstrate the separability of the Hamilton–Jacobi equation for a classical test particle in this spacetime and, using the null Hamilton–Jacobi equation, derive a set of equations that define the black hole shadow’s boundary. Our analysis reveals that the shadow’s shape is influenced by variations in the spacetime parameters, including the Hassan–Sen transformation parameter, which corresponds to the black hole’s electric charge, as well as the NUT charge and rotational parameter. Additionally, we highlight the impact of the Manko–Ruiz parameter on the shadow’s deformation, offering new insights into its role in shaping the Kerr–Sen–Taub–NUT spacetime geometry.