Expositor: Vladimir Karas (Astronomical Institute, Czech Academy of Sciences, Prague, Czech Republic)

Resumen: The presence of non-thermal radio filaments in the Galactic center indicates that supermassive black holes (SMBH) can be embedded in ordered magnetic fields of external origin. We will discuss the effects of particle acceleration that can be expected to occur very close to the event horizon, as the black transits across a magnetic flux tube. Magnetic lines of an aligned field help to launch particles in the direction approximately parallel to the SMBH rotation axis. Oblique magnetic fields lack the axial symmetry and, due to their interplay with frame-dragging near a rotating black hole, the magnetic null points develop. An induced electric component can then efficiently accelerate charged particles. Moreover, we see evidence for the onset of chaos in
the region just above the ergosphere radius.