Quasinormal Modes of a black hole surrounded by a fluid of strings in Rastall gravity

In this paper, we explore the quasinormal modes (QNMs) of a black hole surrounded by a fluid of strings within the framework of Rastall gravity. We analyze the behavior of scalar, electromagnetic, and gravitational perturbations, focusing on the influence of the black hole charge $Q$ and angular momentum $l$ on the quasinormal frequencies. Our numerical results reveal a significant dependence on the parameter $\epsilon$. These trends are consistent across different types of perturbations, emphasizing the relationship between black hole parameters and QNMs behavior.