研究了连续磁岛合并引起的从小尺度到大尺度的磁能转移。一个可解的分析模型,并正确地捕捉到的主要数量的利益,证明了数值模拟的演变。磁重联被认为是实现逆转移的关键机制,并设置其属性:磁能衰减为$\tilde t^{-1}$,其中$\tilde t$是时间归一化的(适当定义的)重联时间尺度;和字段的相关长度增长为$\tilde t^{1/2}$。磁能谱是自相似的,并且演化为$\propto \tilde t ^{-3/2}k^{-2}$,其中$k$依赖性通过薄电流片的形成而赋予。
英文摘要:
Magnetic energy transfer from small to large scales due to successive magnetic island coalescence is investigated. A solvable analytical model is introduced and shown to correctly capture the evolution of the main quantities of interest, as borne out by numerical simulations. Magnetic reconnection is identified as the key mechanism enabling the inverse transfer, and setting its properties: magnetic energy decays as $\tilde t^{-1}$, where $\tilde t$ is time normalized to the (appropriately defined) reconnection timescale; and the correlation length of the field grows as $\tilde t^{1/2}$. The magnetic energy spectrum is self-similar, and evolves as $\propto \tilde t ^{-3/2}k^{-2}$, where the $k$-dependence is imparted by the formation of thin current sheets.
Inverse Transfer in Non-helical 2D Collisionless Magnetic Turbulence: Island-Merger Picture with Kinetic Effects
Tsung-Dao Lee Institute, Shanghai Jiao Tong University(上海交大李政道研究所);School of Mathematics, Physics and Statistics, Shanghai Polytechnic University(上海理工大学数学与统计学院);School of Physics and Astronomy, Shanghai Jiao Tong University(上海交通大学物理与天文学院);Key Laboratory for Particle Physics, Astrophysics and Cosmology (MOE), Shanghai Key Laboratory for Particle Physics and Cosmology, Shanghai Jiao Tong University(上海交通大学粒子物理、天体物理与宇宙学教育部重点实验室)
Double Neutron Star Mergers and Short Gamma-Ray Bursts: Long-Lasting High-Energy Signatures and Remnant Dichotomy
最近从双中子星合并事件GW+ EM 170817中探测到的引力波和电磁波,支持短伽马射线暴(SGRB)和千新星/macronovae的标准范式。重要的是要揭示合并后留下的致密残余物的性质,无论是黑洞还是中子星,以及它们与SGRB中观察到的持久发射起源的物理联系。合并残留物的多样性也可能导致未来可以检测到的不同种类的瞬变。在这里,我们研究的高能量排放的持久的中央引擎后,聚结,在一定的假设。特别是,我们认为X射线辐射从残留盘和非热星云辐射从磁盘驱动的外流或脉冲星风。我们表明,晚时间的X射线和高频无线电发射可以提供有用的约束的隐藏的紧凑的残余物的属性和它们的连接,以持久的SGRB发射,我们讨论了附近的合并事件的可探测性,通过晚时间的观测在合并后的$\sim30-100$ d。我们还调查了GeV-TeV的伽马射线发射,发生在持久的中央引擎的存在下,并显示外部逆康普顿辐射的重要性,由于向上散射的X射线光子的相对论电子在射流。我们还寻找高能γ射线从GW 170817的费米LAT数据,并报告上限,这种持久的排放。最后,我们考虑GW+ EM 170817的影响,并讨论X射线和高频射电观测的限制。
Gravitational Gertsenshtein-Zeldovich mechanism for the Association between GW190425 and FRB 20190425A
School of Fundamental Physics and Mathematical Sciences, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences(杭州高等研究院基础物理与数学科学学院,中国科学院大学);National Astronomical Observatories, Chinese Academy of Sciences(中国科学院国家天文台);Institute of Fundamental Physics and Quantum Technology, Ningbo University(宁波大学基础物理与量子技术研究所);The Hong Kong Institute for Astronomy and Astrophysics, University of Hong Kong(香港大学香港天文与天体物理研究所);Department of Physics, University of Hong Kong(香港大学物理系)
Magnetic Prandtl number dependence of plasmoid-mediated reconnection
International Centre for Theoretical Sciences, Tata Institute of Fundamental Research(国际理论科学中心,塔塔基础研究所);Nordita, KTH Royal Institute of Technology and Stockholm University(诺迪塔,皇家理工学院和斯德哥尔摩大学);The Oskar Klein Centre, Department of Astronomy, Stockholm University(奥斯卡·克莱因中心,天文学系,斯德哥尔摩大学);McWilliams Center for Cosmology & Department of Physics, Carnegie Mellon University(麦克威廉斯宇宙学中心与物理系,卡内基梅隆大学);School of Natural Sciences and Medicine, Ilia State University(自然科学与医学院,伊利亚州立大学)