题目：4D Magnetic field measurement with atomic alignment

摘要：Magnetic field is ubiquitous in the Universe. I would like to present a new direct diagnostic of magnetic fields in diffuse plasma. This technique is based on the alignment (in terms of their angular momentum in the ground state) of atoms and ions with fine or hyperfine splitting of the ground state. A unique feature of this technique is that the properties of the polarized spectral lines (both absorption and emission) depend on the 3D direction of the magnetic field. I shall outline the prospects of the technique and its possible application to studies magnetic fields within circumstellar regions, interplanetary medium, interstellar medium, intergalactic medium. Both spatial and temporal variations of turbulent magnetic field can be traced with this technique as well. In addition, I shall demonstrate that atomic alignment induced by anisotropic radiation can cause polarization of multiple-bands ranging from UV, optical to submilimeter, thus providing a possible way to study magnetic fields in environments where other techniques fail, e.g. at the epoch of Universe reionization. Last but not the least, we find line intensities are modulated by magnetic alignment as well. 

报告人：Yan,Huirong（W3 chair professor at Institut fur Physik und Astronomie,Universitat Potsdam;and Leading Scientist at DESY Zeuthen）

时间：2025年10月17日星期五10:00

地点：紫台3-402

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