Effect of Gravitational Lensing Around a Black Hole in a Dark Matter Halo in the Presence of Plasma

Abstract This article is devoted to the investigation of the observational properties of the Schwarzschild black hole (BH) surrounded by a dark matter (DM) halo. First, we briefly review the spacetime and analyze the event horizon radius. Subsequently, we explore the massive and massless particle dynamics around the Schwarzschild BH surrounded by a dark matter halo, including the innermost stable circular orbit (ISCO) and photon sphere radii. It was found that the radius of the ISCO increases under the influence of the spacetime parameters. Additionally, we investigate weak gravitational lensing with the assumption that the BH is surrounded by a uniform and non-uniform plasma. Finally, we examine the impact of the plasma on the BH shadow and employ Event Horizon Telescope (EHT) observational data to constrain the BH's parameters.