Guest: Dr. Ken-Ichi Nishikawa, University of Alabama in Huntsville, USA
When: 21th May 2018, from 11:00
Where: Institute of Space Science – ISS (Auditorium)
The discovery by Advanced LIGO/Virgo of gravitational waves from the binary neutron star (BNS) merger GW170817 triggered sequential observations of the electromagnetic counterparts, which has opened the era of multi-messenger astronomy. These multi-frequency observations provide us profound information to investigate the processes from the generation of gravitational wave, associated relativistic jets and merger ejecta, and consequently radiation from the interaction of jets and ejecta with interstellar medium. The investigation of these phenomena requires extensive and systematic theoretical and computational research with various observations. In the study of relativistic jets one of the key open questions is their interaction with the environment on the microscopic level. We have studied the initial evolution of both electron–proton and electron–positron relativistic jets containing helical magnetic fields, focusing on their interaction with an ambient plasma. We have performed particle-in-cell simulations of “global” jets containing helical magnetic fields in order to examine how helical magnetic fields affect kinetic instabilities such as the Weibel instability, the kinetic Kelvin-Helmholtz instability (kKHI) and the Mushroom instability (MI) using a larger jet radius. In our previous simulation study, these kinetic instabilities are suppressed and new types of instabilities can grow. In the electron-proton jet simulation a recollimation-like instability occurs near the center of jet. In the electron-positron jet simulation mixed kinetic instabilities grow and the jet electrons are accelerated. In this talk, I will present results of synthetic radiation spectra that are obtained directly from simulations using much larger systems for global jets containing helical magnetic fields., which can then be compared with observations of gamma-ray burst objects. I will also present possible mechanisms of X-ray flare production for such objects due to magnetic reconnection.
Contact person: Dr. Ioana Dutan <idutan[at]spacescience[dot]ro>
This post is also available in: Romanian