Kink-driven magnetic reconnection in relativistic jets: consequences for X-ray polarimetry of BL Lacs

Understand

We investigate with relativistic MHD simulations the dissipation physics of BL Lac jets, by studying the synchrotron polarization signatures of particles accelerated by the kink instability in a magnetically-dominated plasma column.

• The nonlinear stage of the kink instability generates current sheets, where particles can be efficiently accelerated via magnetic reconnection.
• We identify current sheets as regions where s = J d/B is above some predefined threshold (where B is the field strength, J the current density and d the grid scale), and assume that the particle injection efficiency scales as proportional to the square of the current.
• X-ray emitting particles have short cooling times, so they only probe the field geometry of their injection sites.