We present a detailed study of gravitational lensing around a rotating Bañados–Teitelboim–Zanelli (BTZ) black hole in (2 + 1)-dimensional gravity. The study of orbits for massless test particle around this BH spacetime is performed to describe the nature of cosmological constant in lower dimensions. We study the effect of cosmological constant on the photon orbit in view of other critical parameters. The bending angle of light is studied in view of different values of cosmological constant for direct and retrograde motion of test particles. It is being observed that the bending angle slightly decreases as the value of cosmological constant increases in the negative region.

中文翻译：

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旋转的 BTZ 黑洞周围的光偏转

我们详细研究了 (2 + 1) 维引力中旋转的 Bañados–Teitelboim–Zanelli (BTZ) 黑洞周围的引力透镜。围绕这个 BH 时空进行无质量测试粒子的轨道研究是为了描述低维宇宙常数的性质。鉴于其他关键参数，我们研究了宇宙学常数对光子轨道的影响。针对测试粒子的直行和逆行运动的不同宇宙常数值，研究了光的弯曲角。可以观察到，随着宇宙学常数值在负区域的增加，弯曲角略有减小。