Luminosity of accretion disks around rotating regular black holes

Abstract

Abstract We study thin accretion disks in the gravitational field of a class of rotating regular black holes. Our objective is to determine the key parameters governing these accretion disks: the radius of the innermost stable circular orbit $$(r_{\textrm{ISCO}})$$ ( r ISCO ) and the efficiency $$(\eta )$$ ( η ) of the accretion disk in converting matter into radiation. We employ a simplified model to describe the disk’s radiative flux, and differential and spectral luminosity. Subsequently, we compare our findings with the expectations from accretion disks around Kerr black holes. Notably, our calculations reveal that both the luminosity of the accretion disk and its efficiency are greater when considering the geometry of rotating regular black holes, particularly for fixed and small values of the spin parameter (j), in contrast to the predictions obtained using the Kerr metric for a black hole of the same mass. These results offer intriguing insights into the behavior of astrophysical black holes.