Existence of Halos Outside Schwarzschild-f(R) Black Holes

In this paper, we investigate the possibility of the existence of halos around Schwarzschild-f(R) black holes by analyzing the null geodesics of photons in the spacetime. Using a method inspired by the analysis of spherical photon orbits around Kerr-Newman black holes, we explore the conditions under which such halos might exist. Our results suggest that under certain forms of f(R) gravity, halos can indeed form outside the event horizon, providing new insights into the geometry and observational properties of these modified black holes.