Sommaire:

Black hole magnetospheres and jets host collisionless and highly magnetized plasmas that shine across the electromagnetic spectrum. In such plasmas, collisionless magnetic reconnection is an important process, because it can liberate energy stored in the strong magnetic field, accelerating particles that then produce the observed light. To study magnetic reconnection in the collisionless regime relevant here demands a kinetic (as opposed to a fluid, e.g., magnetohydrodynamic) description, and, for this task, the particle-in-cell (PIC) computational method provides a well-suited tool. In this talk, I present two PIC simulation studies of magnetic reconnection as may occur in the jets and magnetospheres of black holes. First, I focus on jets launched by active galactic nuclei and observed head-on as blazars. Here, reconnection couples, at the highest observed photon energies, to electron-positron pair production, leading to radiative signatures reminiscent of gamma-ray flares from flat-spectrum radio quasars. In the second part of my talk, I discuss ongoing efforts to model the accretion of alternating-polarity loops of poloidal magnetic flux onto a spinning black hole. In this context, magnetic reconnection explosively tears the loops open, modifying the polarity of the nascent jet while also providing a potentially observable magnetospheric signal.

Pour plus d'informations, merci de contacter Marcowith A.