Magnetosphere of an orbiting neutron star

Abstract

We conduct force-free simulations of a single neutron star undergoing orbital motion in flat spacetime, mimicking the trajectory of the star about the center of mass on a compact binary system. Our attention is focused on the kinetic energy being extracted from the orbit by the acceleration of the magnetic dipole moment of the neutron star and, particularly, on how this energy gets distributed within its surrounding magnetosphere. A detailed study of the resulting magnetospheric configurations in our setting is presented, incorporating as well the effects due to neutron star spin and the misalignment of the magnetic and orbital axes. We find many features resembling those of pulsar magnetospheres for the orbiting neutron star - even in the absence of spin-of particular interest being the development of a spiral current sheet that extends beyond the light cylinder. Then, we use recent advances in pulsar theory to estimate electromagnetic emissions produced at the reconnection regions of such current sheets.