One of the main scenarios to account for the multi-wavelength flux variability observed in relativistic jets of AGNs is based on diffusive shock acceleration of a population of relativistic electrons on internal shocks of various origins. Any complete AGN emission scenario has to be able to explain the wide range of observed variability time scales between the radio and gamma-ray band. In addition constraints are also provided by very-long-baseline interferometry (VLBI), which shows a large variety of moving and standing emission zones with distinct behaviors. We aim to characterize the evolution of stationary and moving emission zones in the jet and to study their multi-wavelength signatures through emission maps and light curves. We focus our study on flare events that occur during strong interactions between moving ejecta and stationary recollimation shocks. We simulate relativistic jets with the magneto-hydrodynamic code MPI-AMRVAC and inject non-thermal particle distributions of electrons in shock regions. We follow the propagation of a moving shock and its interactions with a structure of standing re-collimation shocks in the jet. Synchrotron emission and radiative transfer are calculated in the post-processing code RIPTIDE for given observation angles and frequencies. We demonstrate the appearance of trailing components behind the leading moving shock. The latter destabilizes the jet, causing the emergence of oscillating standing shocks and relaxation shocks. Emissions from these regions can dominate the overall flux or lead to flare echos in the light curve. Another observational marker of relaxation shocks appears in time-distance plots of bright VLBI components of the jet. Our scenario provides a plausible explanation for radio VLBI observations of the radio-galaxy 3C 111 where trailing components have been observed during a radio outburst event in 1997.
PeV extended emission around Galactic PeVatrons and echos of their flares
Université Paris Cité（巴黎西岱大学）；CNRS, Astroparticule et Cosmologie（法国国家科学研究中心，亚原子粒子与宇宙学）；Laboratory of Astrophysics, École Polytechnique Fédérale de Lausanne（洛桑联邦理工学院天体物理实验室）；Institute for Cosmic Ray Research, The University of Tokyo（东京大学宇宙射线研究所）
Polarization of reflected X-ray emission from the Sgr A molecular complex: multiple flares, multiple sources?
Ludwig-Maximilians-Universität Muenchen（慕尼黑路德维希-马克西米利安大学）；Max Planck Institute for Astrophysics（马普天体物理研究所）；Space Research Institute (IKI)（太空研究所）；INAF Istituto di Astrofisica e Planetologia Spaziali（意大利国家天体物理学和行星学研究所）；NASA Marshall Space Flight Center（美国宇航局马歇尔太空飞行中心）；Université de Strasbourg（斯特拉斯堡大学）；CNRS, Observatoire Astronomique de Strasbourg（法国国家科学研究中心斯特拉斯堡天文台）；Astronomical Institute of the Czech Academy of Sciences（捷克科学院天文研究所）；Center for Astrophysics, Harvard & Smithsonian（哈佛史密森尼天体物理中心）
Search for High-Energy Neutrinos from Infrared Flares
Loyola University Chicago（洛约拉大学芝加哥分校）；Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）；University of Canterbury（坎特伯雷大学）；Université Libre de Bruxelles（布鲁塞尔自由大学）；Niels Bohr Institute, University of Copenhagen（哥本哈根大学尼尔斯玻尔研究所）；TU Dortmund University（多特蒙德工业大学）；University of Kansas（堪萨斯大学）；Bartol Research Institute and Dept. of Physics and Astronomy, University of Delaware（特拉华大学巴托尔研究所及物理与天文学系）；Marquette University（马凯特大学）；Harvard University（哈佛大学）；Michigan State University（密歇根州立大学）；South Dakota School of Mines and Technology（南达科他矿业理工学院）
该研究通过关联红外耀发目录与 IceCube 10 年数据开展时变堆叠分析，未发现显著中微子发射，推导得出红外耀发对 IceCube 100 TeV 弥漫中微子通量的贡献低于 2.7%。
