发表机构
China West Normal University; Chongqing Normal University; Universidade Federal de Campina Grande（西华师范大学; 重庆师范大学; 坎皮纳格兰德联邦大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究结合分析与数值方法，表征膜世界黑洞周围光子运动，揭示图像特征由黑洞自旋等共同控制，重建其光学图像，为额外维度引力模型研究提供理论指导。
AI 中文摘要
本研究考察了Randall–Sundrum膜世界情景下带潮汐荷的旋转黑洞的观测特征。结合基于椭圆积分的分析处理与数值光线追踪，我们详细表征了膜世界黑洞周围的光子运动。对于小观测倾角，次级图像仍嵌在主发射环内部；随着倾角增大，主、次级图像逐渐分离，形成强不对称的图像形态。我们表明，图像不对称性与内阴影的变形由黑洞自旋、潮汐荷和观测倾角共同控制。为分析吸积盘上的频移，我们通过包含 plunge 流将发射区域从 ISCO（最内稳定圆轨道）延伸至事件视界。结果显示，观测倾角是控制频移分布的主导因素。此外，我们使用鱼眼镜头光线追踪模型重建了膜世界黑洞图像，其光学形态与亮度分布对观测频率有明显依赖，尤其在230 GHz与86 GHz的对比中。我们还对比了顺行与逆行吸积盘的亮度分布，发现86 GHz下的总强度和峰值强度均高于230 GHz。对于负潮汐荷值，我们进一步研究了相应的频移行为与230 GHz强度轮廓，可为未来额外维度引力模型的研究提供有用的理论指导。
英文摘要
This work examines the observational signatures of rotating black holes with tidal charge in the Randall--Sundrum braneworld scenario. Combining an elliptic-integral-based analytical treatment with numerical ray tracing, we characterize photon motion around braneworld black holes in detail. For small observer inclinations, secondary images remain embedded inside the primary emission rings. As the inclination becomes larger, the primary and secondary images gradually separate and produce a strongly asymmetric image morphology. We show that the image asymmetry and the deformation of the inner shadow are jointly controlled by the black hole spin, the tidal charge, and the observer inclination. To analyze the frequency shifts across the accretion disk, we extend the emitting region from the ISCO down to the event horizon by including the plunging flow. The results indicate that the observer inclination is the dominant factor governing the frequency-shift distribution. In addition, we reconstruct braneworld black hole images using a fisheye-lens ray-tracing model. The optical morphology and brightness distribution show a clear dependence on the observing frequency, especially when comparing 230~GHz with 86~GHz. We also contrast the brightness distributions of prograde and retrograde disks, finding that both the total intensity and the peak intensity at 86~GHz are higher than those at 230~GHz. For negative values of the tidal charge, we further investigate the corresponding frequency-shift behavior and 230~GHz intensity profiles, which may provide useful theoretical guidance for future studies of extra-dimensional gravity models.
