Simulations of an inhomogeneous stellar wind interacting with a pulsar wind in a binary system

Abstract

Context. Binary systems containing a massive star and a non-Accreting pulsar present strong interaction between the stellar and the pulsar winds. The properties of this interaction, which largely determine the non-Thermal radiation in these systems, strongly depend on the structure of the stellar wind, which can be clumpy or strongly anisotropic, as in Be stars. Aims. We study numerically the influence of inhomogeneities in the stellar wind on the structure of the two-wind interaction region. Methods. We carried out for the first time axisymmetric, relativistic hydrodynamical simulations, with Lorentz factors of ∼6 and accounting for the impact of instabilities, to study the impact in the two-wind interaction structure of an over-dense region of the stellar wind. We also followed the evolution of this over-dense region or clump as it faces the impact of the pulsar wind. Results. For typical system parameters, and adopting a stellar wind inhomogeneity with a density contrast χ >∼ 10, clumps with radii of a few percent of the binary size can significantly perturb the two-wind interaction region, pushing the two-wind interface to