Lepton acceleration by relativistic collisionless magnetic reconnection

We have calculated self-consistent equilibria of a collisionless relativistic electron-positron gas in the vicinity of a magnetic X-point. For the considered conditions, pertinent to extragalactic jets, we find that leptons are accelerated up to Lorentz factors Gamma(0)=kappaeB(0)LE(2)/mc(2)much greater than1, where B-0 is the typical magnetic field strength, Eequivalent toE(0)/B-0, with E-0 the reconnection electric field, L is the length scale of the magnetic field, and kappaapproximate to12. The acceleration is due to the dominance of the electric field over the magnetic field in a region around the X-point. The distribution function of the accelerated leptons is found to be approximately dn/dgamma proportional to gamma(-1) for gammaless than or similar to0. The apparent distribution function may be steeper than gamma(-1) due to the distribution of Gamma(0) values and/or the radiative losses. Self-consistent equilibria are found only for plasma in flow rates to the X-point less than a critical value.