Circular orbits and observational features of the rotating Simpson-Visser black hole surrounded by a thin accretion disk

Abstract

We present a systematic investigation of the radiative properties and optical appearance of rotating SV black holes surrounded by a thin accretion disks, and mainly analyze the influence of the regularization parameter $g$ on related observables. The results show that although the kinetic quantities and the location of the innermost stable circular orbit (ISCO) depend on the regularization parameter $g$, the radiative efficiency of the rotating SV black hole is the same as its Kerr counterpart. Within the Novikov-Thorne thin-disk model, the radiative flux, effective temperature, and spectral luminosity are studied, and by adopting observational parameters relevant to SgrA* and M87*, concrete examples of the rotating SV black holes are calculated and compared with that of the Kerr black holes. The results show that the parameter $g$ suppresses the maximum values of these quantities. In addition, using a backward ray-tracing technique, we numerically simulate the optical appearance of rotating SV black holes and analyze the corresponding intensity images, redshift and observed flux distributions. Our results show that these quantities are affected by $g$. In particular, as $g$ increases, the observed intensity is significantly suppressed and the photon ring region has remarkable increase in its width. Our findings suggest that accretion-disk-related observables may provide important avenues to distinguish rotating SV black holes and Kerr black holes, and offer theoretical guidance for future high-resolution observations.