סמינר באסטרונומיה ובאסטרופיזיקה: Lighting up magnetic jets: 3D instabilities and energy dissipation in relativistic MHD jets.

Abstract:

It is commonly accepted that the relativistic jets observed in extragalactic sources like GRBs and AGNs are launched magnetically and are powered by the rotational energy of a central object. Such jets carry most of their energy in the form of electromagnetic Poynting flux. However by the time the ejecta reach the emission zone most of that energy is transferred to relativistic motions of the jet material with a large fraction given to non thermal particles, which calls for an efficient dissipation mechanism to work within the jet without compromising its integrity. Understanding how Poynting dominated jets can dissipate their energy is therefore crucial for modeling these astrophysical objects. In this talk I will present the first self consistent 3D simulations of the formation and propagation of highly magnetized (σ~25), relativistic jets in a dense medium. I will show how the magnetic energy in the jets is efficiently dissipated, reaching a state of equipartition between the magnetic and thermal energies. I will also show how this equilibrium state stabilizes the jets from being disrupted by magnetic instabilities. I will discuss the interesting implications from these results on the energy emission in GRBs and the type of compact objects that power them. I will show how GRBs are connected with super luminous supernovae, and what sets them apart from each other. Finally, I will present a new scheme that addresses the dichotomy between FRI and FRII radio galaxies.

מארגת הסמינר: פרופ' שרה בק