Gamma-ray pulsars: What have we learned from ab-initio kinetic simulations?

Abstract

The origin of the pulsed gamma-ray emission in pulsars remains an open issue. The combination of sensitive observations in the GeV domain by AGILE and {\em Fermi}-LAT and increasingly sophisticated numerical simulations have recently brought new insights into our understanding of the pulsed emission and particle acceleration processes in pulsars. Particle-in-cell simulations of pulsar magnetospheres show that the equatorial current sheet forming beyond the light cylinder is the main culprit for magnetic dissipation, particle acceleration and bright high-energy synchrotron radiation all together. The shinning current sheet naturally results in a pulse of light each time the sheet crosses our line of sight, which happens twice in most cases. Synthetic lightcurves present robust features reminiscent of observed gamma-ray pulsars by the {\em Fermi}-LAT and AGILE, opening up new perspectives for direct comparison between simulations and observations.