报告题目：MHD simulations of collision-induced magnetic reconnection in Poynting-flux-dominated jets and interpretation to the polarization observations of GRBs and blazar flares

　　报告人：Dr. Wei Deng (邓巍) （University of Nevada, Las Vegas）

　　摘要：The energy composition in the jet/outflow of astrophysical systems is an important and fundamental question. Recently, the collision-induced magnetic reconnection and dissipation models in the Poynting-flux-dominated (PFD) environment become more attractive to overcome some criticisms in the traditional matter-flux-dominated (MFD) models and interpret new observations. Here, we perform 3D relativistic MHD simulations to study the collisions between high-sigma (PFD) blobs which contain both poloidal and toroidal magnetic field components to mimic the above considerations. Our results strongly support these considerations from the energy dissipation efficiency (> 35%) and the mini-jets generation point of view. We also find a possible relationship between the $\sigma$ values before and after the major EMF energy dissipation process. On the other hand, polarization observation is another important and independent information to constrain the energy environment and physical models. Here we study the polarization feature based on the magnetic field evolution from our above MHD simulation, and find that it can simultaneously interprets the representative polarization observations for both Gamma-Ray Bursts (GRBs) and blazar flares quite well and concisely. This result also strongly supports the above PFD considerations. And more interestedly, it hints that, for some cases, the GRBs prompt emission and the blazar flares may share similar physical process and energy environment.

　　时间：2015年10月28日 星期三 下午16:00

　　地点：（北京西路2号）紫台大楼317会议室

　　联系人：谢洁（83332228）

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　　                                              紫金山天文台学术委员会