JCAP, 08, 041 (2024)
Shadows, rings and optical appearance of a magnetically charged regular black hole illuminated by various accretion disks
Soroush Zare1, Luis M. Nieto1, Xing-Hui Feng2, Shi-Hai Dong3,4 and Hassan Hassanabadi5
1 Departamento de Física Teórica, Atómica y Optica and Laboratory for Disruptive, Interdisciplinary Science (LaDIS), Universidad de Valladolid, 47011 Valladolid, Spain.
2 Center for Joint Quantum Studies and Department of Physics, School of Science, Tianjin University, Tianjin 300350, China.
3 Research Center for Quantum Physics, Huzhou University, Huzhou, 313000, P.R. China.
4 Centro de Investigación en Computación, Instituto Politécnico Nacional, UPALM, CDMX 07700, Mexico.
5 Department of Physics, Faculty of Science, University of Hradec Králové, Rokitanského 62, 500 03 Hradec Králové, Czech Republic.
* szare@uva.es, luismiguel.nieto.calzada@uva.es, xhfeng@tju.edu.cn, dongsh2@yahoo.com, hha1349@gmail.com
Abstract
The Event Horizon Telescope (EHT) imaging of the supermassive black holes at the centers of Messier 87 galaxy (M87) and the Milky Way galaxy (Sgr A) marks a significant step in observing the 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 and spherically symmetric magnetically charged regular black hole (MCRBH) metric characterized by its mass and an additional parameter q, which arises from the coupling of Einstein gravity and nonlinear electrodynamics (NLED) in the weak field approximation. This parameterized model offers a robust foundation for testing the coupling of Einstein gravity and NLED in the weak-field approximation, using the EHT observational results. In this study, we investigate the geodesic motion of particles around the solution, followed by a discussion of its fundamental geometrical characteristics such as scalar invariants. Using null geodesics, we examine how the model parameter influences the behavior of the photon sphere radius and the associated shadow silhouette. 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 are susceptible to variations in q, which can have an impact on the traits of the innermost stable circular orbit and the marginally bounded orbit. Our primary objective is to probe how the free parameter q affects various aspects of the accretion disk surrounding the MCRBH using the thin-disk approximation. Next, we discuss the physical characteristics of the thin accretion disk as well as the observed shadows and rings of the MCRBH, along with its luminosity, across various accretion models. Ultimately, variations in accretion models and the parameter q yield distinct shadow images and optical appearances of the MCRBH.
