Light Rings, Accretion Disks and Shadows of Hayward Boson Stars in asymptotically AdS Spacetime

Abstract: In this paper, we employ numerical methods to investigate the fundamental properties of Hayward boson stars and the optical appearance of their accretion disks in asymptotically anti-de Sitter (AdS) spacetime. Our results show that variations in the negative cosmological constant significantly affect the relationship between ADM mass and frequency, the critical magnetic monopole charge, the size of the photon ring, and the kinematic characteristics of particles at the innermost stable circular orbit (ISCO). Through ray-tracing studies of the accretion disk's appearance, we find that for non-frozen boson stars, the absence of an event horizon leads to multiple photon rings appearing within the central shadow region. In contrast, for frozen boson stars, the presence of a critical event horizon causes their images to resemble those of Schwarzschild black holes, with no additional photon rings appearing within the shadow region. Furthermore, the negative cosmological constant significantly alters the image structure: a smaller ISCO radius leads to photon rings being obscured at specific viewing angles, preventing their appearance within the shadow region.