Thin accretion disc luminosity and its image around rotating black holes in perfect fluid dark matter
Abstract
ABSTRACT Motivated by the fact that the universe is dominated by dark matter and dark energy, we consider rotating black holes surrounded by perfect fluid dark matter and study the accretion process in thin disc around such black holes. Here, we are interested in how the presence of dark matter affects the properties of the electromagnetic radiation emitted from a thin accretion disc. For this purpose, we use the Novikov–Thorne model and obtain the electromagnetic spectrum of an accretion disc around a rotating black hole in perfect fluid dark matter and compare with the general relativistic case. The results indicate that for small values of dark matter parameter we considered here, the size of the innermost stable circular orbits would decrease and thus the electromagnetic spectrum of the accretion disc increases. Therefore, discs in the presence of perfect fluid dark matter are hotter and more luminous than in general relativity. Finally, we construct thin accretion disc images around these black holes using the numerical ray-tracing technique. We show that the inclination angle has a remarkable effect on the images, whereas the effect of dark matter parameter is small.