Redshift of photons emitted from the accretion disk of a regular black hole surrounded by dark matter

Abstract

In this paper, we have investigated the motion of photons as well as the frequency shift of photons emitted by geodesic particles influenced by the central black hole (BH) described by Bardeen solution surrounded by perfect fluid dark matter (PFDM). It has been shown that in general there are two stable photon spheres formed due to the gravitational attraction of photons by the central gravitating compact object. It has been obtained that with the increase of the space–time parameters these photon spheres come close to each other until they merge forming unique photon sphere around central BH. Investigation of the frequency shift of photons radiated by the particles geodesically moving in the equatorial plane has shown that the former becomes stronger for the bigger values of the intensity of PFDM and smaller values of the magnetic charge of the Bardeen solution.