We revisit the shadows of rotating braneworld black holes in the Randall-Sundrum type II model, by considering not only the metric in the near region of the black hole but also the linearized metric in the far region where the observer stays. Our study is significantly different from previous studies, which relies only on the metric in the near region. From the study, we identify a critical angle $θ_c$ which decides the shadow curve is open or closed: the shadow curve would be open if the observational angle $θ_c<θ_o\leπ/2$, and the curve becomes closed when $0<θ_o\leθ_c$. We study how various parameters affect the shape of the shadow curve. We furthermore apply our analysis to the data of M87* from the Event Horizon Telescope and obtain a new constraint on the parameters of the braneworld black holes.
Revisiting critical orbits of test particles traveling in a black hole background
College of Mathematics and Physics, Hunan University of Arts and Sciences（湖南文理学院数学与物理学院）；Hunan Province Key Laboratory Integration and Optical Manufacturing Technology（湖南省集成与光学制造技术重点实验室）；Center for Astrophysics, Guangzhou University（广州大学天体物理中心）
Observable strong field effects of extra spacetime dimension in the braneworld black hole
M. Akmullah Bashkir State Pedagogical University（M.阿克穆拉·巴什基尔国立师范学院）；University of North Bengal（北孟加拉大学）；Ufa University of Science & Technology, Sterlitamak Campus（乌法科学技术大学斯特利塔马克校区）
