Kerr-like black hole surrounded by cold dark matter halo: the shadow images and EHT constraints

Abstract Here we provide shadow images of a Kerr-like black hole (BH) in cold dark matter (CDM) halo illuminated with a celestial light source and a thin accretion disk. The impact of spin parameter a , critical density ρ c and the scale radius R s on the observed images of BHs is carefully addressed. The results indicate that as a increases, the circular orbits are shifted rightwards, while the larger values of both ρ c and R s are the cause to enhance the radius of circular orbits of the BH shadow. In the case of the celestial light source, the impact of ρ c on shadow distortion is negligible, but this influence is relatively smaller and becomes appreciable when the parameter R s has larger values. Next, we discuss the intensity and the size of the inner shadow, which are gradually increasing with the increase of both ρ c and R s . On the other hand, in the case of retrograde flow, the intensity of the shadow images significantly decreases, and a crescent moon emerges on the upper right side of the screen. Subsequently, the distinctive features of red-shift factors for direct and lensed images with prograde and retrograde flows are discussed. The outcomes indicate that the distribution of red-shift factors and the optical appearance are closely related to the behaviour of accreting flow as well as with relevant parameters. Using the recent observational data of EHT, we found that the shadow's angular diameter of Sgr A * provides the best-fit parameter constraints as compared to M87*.