Pulsars with bow shocks: Model constraints of the pulsar wind Lorentz factor

Abstract

Pulsar wind nebulae with bow shocks (BSPWNe) can efficiently accelerate electrons and positrons of the pulsar wind (PW). The particles injected into such nebulae at the PW termination shock can gain energy due to the Fermi acceleration in the colliding shock flow between the two shocks. Monte-Carlo modeling of the PW particle transport through the nebula reveals a significant deformation of their spectrum between the shocks in comparison with the injected spectrum. The maximal energies achieved by the hard component of the spectrum (f (E) ∝ E -p with p 2) depend on the flow velocities. Comparison of the obtained spectra of the accelerated PW particles in BSPWNe and their synchrotron emission maps with the observational data obtained in the optical, far-UV and X-ray bands allows one to constrain global parameters of particular BSPWNe such as Lorentz-factors of their PWs.