Variable $γ$-ray flares upto minute timescales reflect extreme particle acceleration sites. However, for high-redshift blazars, the detection of such rapid variations remains limited by current telescope sensitivities. Gravitationally lensed blazars serve as powerful tools to probe $γ$-ray production zones in distant sources, with time delays between lensed signals providing crucial insights into the spatial distribution of emission regions relative to the lens's mass-weighted center. We have utilized 15 years of Fermi-LAT $γ$-ray data from direction of PKS 1830$-$211 to understand the origin of flaring high-energy production zone at varying flux states. To efficiently estimate the (lensed) time delay, we used a machine learning-based tool - the Gaussian Process regression algorithm, in addition to - Autocorrelation function and Double power spectrum. We found a consistent time delay across all flaring activity states, indicating a similar location for the $γ$-ray emission zone, possibly within the radio core. The estimated time delay of approximately 20 days for the five flaring epochs was significantly shorter than previously estimated radio delays. This suggests that the $γ$-ray emission zone is closer to the central engine, in contrast to the radio emission zone, which is expected to be much farther away. A linear relationship between lag and magnification has been observed in the identified source and echo flares. Our results suggest that the $γ$-ray emission zone originates from similar regions away from the site of radio dissipation.
Gamma-ray Time Delay and Magnification Ratio in the Gravitationally-Lensed Blazar PKS 1830-211
Julius-Maximilians-Universität Würzburg（维尔茨堡大学）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）；SISSA（国际高等研究学院）；KTH Royal Institute of Technology（皇家理工学院）；Naval Research Laboratory（海军研究实验室）；Istituto Nazionale di Fisica Nucleare, Sezione di Perugia（意大利国家核物理研究所佩鲁加分部）；Università degli Studi di Perugia（佩鲁贾大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Roma “Tor Vergata,”（意大利国家核物理研究所罗马“托维加塔”分部）；Space Science Data Center - Agenzia Spaziale Italiana（意大利航天局空间数据中心）；University of Pisa（比萨大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Pisa（意大利国家核物理研究所比萨分部）
Probing the jet base of the blazar PKS1830-211 from the chromatic variability of its lensed images. Serendipitous ALMA observations of a strong gamma-ray flare
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。
Submillimeter polarization and variability of quasar PKS 1830-211
活动星系核的偏振被解释为磁场在发射和准直相对论射电喷流中的作用的路标。在这里，我们报告了一个清晰的偏振信号的ALMA观测引力透镜类星体PKS 1830-211在亚毫米波长（波段9，650 GHz）的检测。将差分偏振测量技术应用于类星体的两张紧凑透镜图像，我们估计一张透镜图像的分数偏振约为5%，而另一张图像几乎未偏振，这意味着偏振活动在几周的时间尺度上变化。随着额外的ALMA波段7和8（300-500 GHz之间）的伴随数据，我们约束几个$10^5$ rad m $^{-2}$的法拉第旋转。我们还观察到在波段9中一小时内通量密度变化约为10%。这项工作表明，差分分析可以提取高精度的信息（通量密度比和偏振）的校准问题，从解决来源在亚毫米域。
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）
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）
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。
