Datensatz

Zusammenfassung

Pulsars moving through interstellarmedium (ISM) produce bow shocks detected in hydrogen H alpha line emission. Themorphology of the bow shock nebulae allows one to probe the properties of ISM on scales similar to 0.01 pc and smaller. We performed 2D relativistic magnetohydrodynamic modelling of the pulsar bow shock and simulated the corresponding Ha emission morphology. We find that even a mild spatial inhomogeneity of ISM density, delta rho/rho similar to 1, leads to significant variations of the shape of the shock seen in Ha line emission. We successfully reproduce the morphology of the Guitar Nebula. We infer quasi-periodic density variations in the warm component of ISM with characteristic length of similar to 0.1 pc. Structures of this scale might be also responsible for the formation of the fine features seen at the forward shock of Tycho supernova remnant (SNR) in X-rays. Formation of such short periodic density structures in the warm component of ISM is puzzling, and bow-shock nebulae provide unique probes to study this phenomenon.