Shadows, rings and optical appearance of a magnetically charged regular black hole illuminated by various accretion disks

• Published in: Journal of cosmology and astroparticle physics Vol. 2024; no. 8; pp. 041 - 77
• Main Authors: Zare, Soroush, Nieto, Luis M., Feng, Xing-Hui, Dong, Shi-Hai, Hassanabadi, Hassan
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 01.08.2024
• Subjects: accretion; Accretion disks; Approximation; Black holes; Coupling; Electrodynamics; Elliptical galaxies; Event horizon; Geodesy; GR black holes; Gravity foundations; Luminosity; Milky Way; modified gravity; Parameters; Photons; Physical properties; Rings (mathematics); Shadows; Supermassive black holes
• ISSN: 1475-7516; 1475-7516
• DOI: 10.1088/1475-7516/2024/08/041

The Event Horizon Telescope (EHT) imaging of the supermassive black holes at the centersof Messier 87 galaxy (M87) and the Milky Way galaxy (Sgr A) marks a significant step in observingthe photon rings and central brightness depression that define the optical appearance of blackholes with an accretion disk scenario. Inspired by this, we take into account a static andspherically symmetric magnetically charged regular black hole (MCRBH) metric characterized by itsmass and an additional parameter q, which arises from the coupling of Einstein gravity andnonlinear electrodynamics (NLED) in the weak field approximation. This parameterized modeloffers a robust foundation for testing the coupling of Einstein gravity and NLED in theweak-field approximation, using the EHT observational results. In this study, we investigate thegeodesic motion of particles around the solution, followed by a discussion of its fundamentalgeometrical characteristics such as scalar invariants. Using null geodesics, we examine how themodel parameter influences the behavior of the photon sphere radius and the associated shadowsilhouette. We seek constraints on q by applying the EHT results for supermassive black holesM87* and Sgr A*. Furthermore, it is observed that the geodesics of time-like particles aresusceptible to variations in q, which can have an impact on the traits of the innermost stablecircular orbit and the marginally bounded orbit. Our primary objective is to probe how the freeparameter q affects various aspects of the accretion disk surrounding the MCRBH using thethin-disk approximation. Next, we discuss the physical characteristics of the thin accretiondisk as well as the observed shadows and rings of the MCRBH, along with its luminosity, acrossvarious accretion models. Ultimately, variations in accretion models and the parameter q yielddistinct shadow images and optical appearances of the MCRBH.