By means of two- and three-dimensional particle-in-cell simulations , we investigate the process of driven magnetic reconnection at the termination shock of relativistic striped flows .
In pulsar winds and in magnetar-powered relativistic jets , the flow consists of stripes of alternating magnetic field polarity , separated by current sheets of hot plasma .
At the wind termination shock , the flow compresses and the alternating fields annihilate by driven magnetic reconnection .
Irrespective of the stripe wavelength \lambda or the wind magnetization \sigma ( in the regime \sigma \gg 1 of magnetically-dominated flows ) , shock-driven reconnection transfers all the magnetic energy of alternating fields to the particles , whose average Lorentz factor increases by a factor of \sigma with respect to the pre-shock value .
In the limit \lambda / ( r _ { L } \sigma ) \gg 1 , where r _ { L } is the relativistic Larmor radius in the wind , the post-shock particle spectrum approaches a flat power-law tail with slope around -1.5 , populated by particles accelerated by the reconnection electric field .
The presence of a current-aligned “ guide ” magnetic field suppresses the acceleration of particles only when the guide field is stronger than the alternating component .
Our findings place important constraints on the models of non-thermal radiation from Pulsar Wind Nebulae and relativistic jets .