Imaging the destruction of a rotating regular black hole (2503.07011v2)

Abstract: A regular black hole, unconstrained by the weak cosmic censorship conjecture, can exceed its critical spin limit and transition into a superspinar. In this paper, we investigate the observational appearance of a rotating regular black hole, specifically the Ghosh black hole and its superspinar counterpart, when surrounded by a thin accretion disk. The resulting images reveal distinct features: the black hole closely resembles its Kerr counterpart with slight deviations, while the superspinar configuration exhibits an inner photon ring structure. Furthermore, we explore the image transition of the Ghosh black hole that has been recently destroyed by the capture of a test particle. The results show that the inner photon ring undergoes gradual transitions over time, which depend on the additional angular momentum gained by the black hole. Our findings also suggest that the transition timescale becomes relevant for supermassive black holes with masses approximately twice that of M87*, making these effects potentially observable with future high-resolution instruments.