Properties of Accretion Discs Around Black Holes Through Modelling

Abstract

We examine accretion discs within the context of Einstein's general relativity. We use the metrics corresponding to the four black hole solutions proposed by Einstein, with the Shakura-Sunyaev model of the disc. Starting from the definition of the "no-hair theorem" that a black hole only stores information about three main parameters — mass, angular momentum and charge — we tested the impact of varying these parameters, emphasising the relations between them. Moreover, the research we present here captures and illustrates two pivotal aspects predicted by general relativity: the circular photon ring and the frame-dragging effects of the ergosphere. Our research delves into emissivity profiles, exploring both the well-established lamp post model and the beamed point source model. We reproduced the results from the literature and noted the inconsistencies between the works and our results while also providing an alternative source supporting our results. Altogether, this work presents a comprehensive exploration of accretion disc dynamics around central compact objects within the framework of Einstein's general relativity, shedding light on intricate phenomena that continue to captivate the scientific community.