讲座时间：2020-04-03 20:00
讲座地点： ZOOM 直播
主讲人：Yosuke Mizuno
主办单位：李政道研究所
联系人：石井花 (leeastronomy@sjtu.edu.cn)




Yosuke Mizuno obtained a PhD in astrophysics with a thesis on general relativistic magnetohydrodynamic simulations of collapsar as a central engine of gamma-ray bursts. Since April 2004, he was a postdoc at Department of Astronomy, Kyoto University, Japan (2004-05), NASA postdoctoral program fellow at NASA Marshall space flight center, USA (2005-08), research scientist at University of Alabama in Huntsville, USA (2008-11), and assistant research scholar at National Tsing Hua University (2011-2014). From October 2014, he is a research associate at Institute for Theoretical Physics, Goethe University Frankfurt, Germany. He is a Theory & Simulation Working Group coordinator (2017-present) on Event Horizon Telescope collaboration. He has worked on relativistic astrophysics, black hole astrophysics, plasma astrophysics, and high-energy astrophysics by using numerical simulations. The research is black hole, active galactic nuclei, gamma-ray bursts, astrophysical jets, and accretion flow. The research area is covered fundamental plasma physics including shocks, instabilities, turbulence, magnetic reconnection and particle acceleration. Recently he has also studied theory of gravity via black hole shadow.
产生和加速相对论喷流，以及维持相对论喷流从吸积流进入到黑洞的准直结构的最有希望的机制涉及磁流体动力学（MHD）过程。我们通过广义相对论磁流体动力学模拟研究了磁场在相对论喷流和黑洞吸积流中的作用。我们发现，包含螺旋磁场的相对论喷流会因为一种流驱动的扭结不稳定性而不稳定，这导致相对论喷流中出现螺旋扭曲的结构，并在磁重联过程中耗散喷流的磁能。我们发现过压下相对论喷流会产生一系列稳定再准直冲击和稀松结构，这些结构对应于相对论喷流中观察到的稳定发射成分。报告中还介绍了我们新的3D AMR-GRMHD程序BHAC及其在黑洞吸积流进入黑洞过程中的应用，以捕捉黑洞的观测特征，即EHT项目和VLBI项目观测到的所谓黑洞阴影。

The most promising mechanisms for producing and accelerating relativistic jets, and maintaining collimated structure of relativistic jets from accretion flows onto black holes involve magnetohydrodynamical (MHD) processes. We have investigated the role of magnetic field in relativistic jets and accretion flows onto black hole via general-relativistic MHD simulations.I found that relativistic jets involving helical magnetic field are unstable via a current-driven kink instability, which leads to helically distorted structure in relativistic jets and dissipates the jet's magnetic energy through magnetic reconnection. I found that an over-pressured relativistic jet leads to the generation of a series of stationary recollimation shocks and rarefaction structures which corresponds to stationary emission components observed in relativistic jets. I also present our new 3D AMR-GRMHD code BHAC and its application to black-hole accretion flows onto a black hole to capture the observational signatures of a black-hole, so-called black hole shadow observed by EHT and future space VLBI.
Zoom链接：https://zoom.com.cn/j/315763232 会议号：315763232; 密码：813168
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