3D magnetohydrodynamic simulations of runaway pulsars in core-collapse supernova remnants

Context. Pulsars represent one of the possible final stages in the evolution of massive stars. If a supernova explosion is anisotropic, it can give the pulsar a powerful “kick”, propelling it to supersonic speeds. The resulting pulsar wind nebula is significantly reshaped by its interaction with the surrounding medium as the pulsar moves through it. First, the pulsar crosses the supernova remnant (SNR), followed by the different layers of circumstellar medium (CSM) formed during different stages of the progenitor star’s evolution. Aims. We aim to investigate how the evolutionary history of massive stars shapes the bow shock nebulae of runaway “kicked” pulsars and how these influences then go on to affect the dynamics and non-thermal radio emission of the entire pulsar remnant. Methods. We performed three-dimensional magnetohydrodynamic (3D MHD) simulations using the PLUTO code to model the pulsar wind nebula generated by a runaway pulsar in the SNR of a red supergiant progenitor and derive its non-thermal radio emission. Results. The SNR and the pre-supernova CSM of the progenitor strongly confine and reshape the pulsar wind nebula of the runaway pulsar, bending its two side jets inward and giving the nebula an arched shape with respect to an observer perpendicular to the jets and the propagation direction, as observed around PSR J1509–5850 and Gemina. Conclusions. We performed the first classical 3D model of a pulsar moving inward through its supernova ejecta and CSM, inducing a bending of its polar jet that turns into characteristic radio synchrotron signature. The CSM of young runaway pulsars has a significant influence on the morphology and emission of pulsar wind nebulae and our understanding of this scenario requires a detailed grasp of the evolutionary history of the progenitor star.