|Time:||Tuesday, September 22, 2020, 10:30am|
|Title:||Magnetodynamics inside and outside magnetars|
|Speaker:||Dr. Xinyu Li (CITA/Perimeter Institute)|
Online via Zoom
Magnetars have magnetic field up to 10^15 G. The ultra-strong magnetic field has profound implications for the mechanical, thermal and radiative evolution of magnetars. In this talk, I will discuss the conversion of magnetic energy to radiations inside and outside magnetars. Inside the magnetar, we studied the interaction between the magnetodynamics and the mechanical responses of the crust. Internal Hall waves launched from the core-crust interface can develop large magnetic stress that initiate plastic deformation of the crust and power the observed X-ray outbursts. Outside the magnetar, we studied how Alfven waves is dissipated in the magnetosphere. Using a high order simulation of Force-Free Electrodynamics (FFE), we found that the turbulent dissipation of Alfven waves is slow compared to the absorption of waves by the magnetar crust. However, FFE is not applicable when magnetic dominance (magnetic field larger than the electrical field) is lost. In that situation, we demonstrated with kinetic simulations that a transient current sheet is formed with increased gradient of the local magnetic field. Magnetic reconnection can be triggered in 2D which accelerates particles and provides a new channel of dissipation.
Xinyu Li（李昕宇） is currently a joint postdoctoral fellow at Canadian Institute for Theoretical Astrophysics and Perimeter Institute. His research interests include theoretical high energy astrophysics, cosmology and plasma astrophysics. He obtained his PhD degree in physics at Columbia University. Before that, he earned his Bachelor degree from the University of Hong Kong and spent his first year of undergraduate at Tsinghua University.
Host: Shude Mao