Modelling the bow shock Pulsar Wind Nebulae propagating through a non-uniform ISM

Abstract

Many pulsars propagate through the interstellar medium (ISM) with supersonic velocities, and their pulsar winds interact with the interstellar medium (ISM), forming bow shocks and magnetotails (PWN). We model the propagation of pulsars through the inhomogeneous ISM using non-relativistic axisymmetric magneto-hydrodynamic (MHD) simulations. We take into account the wind from the star, and the azimuthal and poloidal components of the magnetic field, and investigate the PWN at different levels of magnetization (the ratio of magnetic to matter energy-densities) in the wind. We consider the interaction of PWN with small-scale and large-scale imhomogeneities in the ISM at different values of magnetization. We conclude that the inhomogeneities in the ISM can change the shapes of the bow shocks and magnetotails at different values of the magnetization.We compare the results of our simulations with the images of the Guitar Nebula and other PWN that show irregularities in the shapes of their bow shocks and magnetotails. We conclude that these irregularities may be caused by the interaction of PWN with the inhomogeneities in the ISM.