Title: MHD simulations of GRB (gamma-ray burst) and blazar flares

　　Speaker: Wei Deng (University of Nevada, Las Vegas)

　　Time: Oct. 29, Thursday, 2pm

　　Location: the middle conference room

　　Abstract:

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 ($\geq 35\%$) 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..