If gamma-ray bursts are at cosmological distances, they must be gravitationally lensed occasionally. The detection of lensed images with millisecond-to-second time delays provides evidence for intermediate-mass black holes, a population that has been difficult to observe. Several studies have searched for these delays in gamma-ray burst light curves, which would indicate an intervening gravitational lens. Among the $\sim 10^4$ gamma-ray bursts observed, there have been a handful of claimed lensing detections, but none have been statistically robust. Here we present a Bayesian analysis identifying gravitational lensing in the light curve of GRB950830. The inferred lens mass depends on the unknown lens redshift $z_l$, and is given by $(1+z_l)M_l = 5.5^{+1.7}_{-0.9}\times 10^4 $ M$_\odot$ (90% credibility), which we interpret as evidence for an intermediate-mass black hole. The most probable configuration, with a lens redshift $z_l\sim 1$ and a gamma-ray burst redshift $z_s\sim 2$, yields a present day number density of $n_\text{imbh}\approx 2.3^{+4.9}_{-1.6}\times10^{3} \text{ Mpc}^{-3}$ (90% credibility) with a dimensionless energy density $Ω_\text{imbh} \approx 4.6^{+9.8}_{-3.3}\times10^{-4}$. The false alarm probability for this detection is $\sim0.6\%$ with trial factors. While it is possible that GRB950830 was lensed by a globular cluster, it is unlikely since we infer a cosmic density inconsistent with predictions for globular clusters $Ω_\text{gc} \approx 8 \times 10^{-6}$ at 99.8% credibility. If a significant intermediate-mass black hole population exists, it could provide the seeds for the growth of supermassive black holes in the early Universe.
Test of relativistic gravity using microlensing of relativistically broadened lines in gravitationally lensed quasars
我们表明，在强透镜类星体中观测相对论性加宽的发射线（例如X射线中的Fe K α线）的微透镜效应的时间依赖性，可以提供超大质量黑洞视界附近圆形轨道的天体力学数据。该信息可以从放大线的红/蓝边缘的演化的观察中提取，所述红/蓝边缘刚好在微透镜焦散线穿过最内侧稳定圆形轨道的周期之前和之后。这种演化的函数形式对吸积黑洞和微透镜焦散网络系统的许多天体物理参数不敏感（与全谱线的演化相反）。测量红/蓝边缘的时间演化可以精确测量引力红移和圆形轨道速度的径向依赖性，直到最里面的稳定圆形轨道。这些测量可以用来区分广义相对论和相对论引力的替代模型，其中光子和大质量物体绕引力中心的动力学不同于史瓦西或克尔时空中的测地线。
Reflection From the Strong Gravity Regime in a z=0.658 Gravitationally Lensed-Quasar
超大质量黑洞与其宿主星系在宇宙时间中的共同演化被编码在其自旋中。在$z>2$，超大质量黑洞被认为主要是通过合并驱动的吸积导致高自旋而生长的。然而，在$z\sim1$以下，这些黑洞是通过相干吸积还是以混沌的方式继续增长，这是未知的，尽管预测它们的自旋演化有明显的差异。测量黑洞自旋的一个既定方法是通过研究来自内吸积盘的相对论反射特征。由于它们的距离更远，迄今为止还没有在中等红移类星体中发现相对论反射特征。在这里，我们使用档案数据与一个新的，在$z=0.658$引力透镜类星体的深度观测严格检测和研究在这个中等红移类星体的反射。在这个反射光谱中存在的相对论性畸变水平使我们能够将发射限制在来自黑洞的$\lesssim3$引力半径内，这意味着在$3σ$置信水平上的自旋参数$a=0.87^{+0.08}_{-0.15} $和在$5σ$水平上的$a>0.66$。这里发现的高自旋是通过相干吸积这个黑洞的增长的指示，并建议$0.5\lesssim z \lesssim 1$之间的黑洞增长主要发生在相干吸积事件，而不是混乱。
An archival search for gamma-ray bursts gravitationally lensed by galaxy clusters
Institute of Cosmology and Gravitation, University of Portsmouth（宇宙学与引力研究所，朴茨茅斯大学）；School of Physics and Astronomy, University of Birmingham（物理与天文学学院，伯明翰大学）；Institute for Gravitational Wave Astronomy, University of Birmingham（引力波天文学研究所，伯明翰大学）；Department of Astrophysics, University of Vienna（天体物理学系，维也纳大学）
High-energy variability of the gravitationally lensed blazar PKS 1830-211
Stanford University（斯坦福大学）；SLAC National Accelerator Laboratory（斯坦福直线加速器中心）；Institut de Física d’Altes Energies (IFAE)（高能物理研究所）；The Barcelona Institute of Science and Technology (BIST)（巴塞罗那科学与技术研究院）；NASA Ames Research Center（美国国家航空航天局艾姆斯研究中心）；Washington University in St. Louis（华盛顿大学圣路易斯分校）；Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences（波兰科学院尼古拉·哥白尼天文学中心）
Detectability of Gravitationally Lensed Kilonovae in the Rubin LSST
Inter-University Centre for Astronomy and Astrophysics（天文与天体物理大学间中心）；Kavli Institute for the Physics and Mathematics of the Universe (IPMU)（宇宙物理与数学卡弗里研究所）
