Global Simulations of the Interaction of Microquasar Jets with a Stellar Wind in High-Mass X-ray Binaries

TL;DR

This paper presents the first 3D simulations of how jets from high-mass X-ray binaries interact with stellar winds, revealing jet bending behavior that can help estimate jet power and constrain models of these systems.

Contribution

It introduces novel 3D simulations of jet-wind interactions in high-mass X-ray binaries and derives analytical expressions linking jet bending to jet power and wind properties.

Findings

Jet bending can be used to estimate jet power from observed angles.

In Cygnus X-1, jet power is constrained to be above 10^{36} erg/s.

Jet bending is negligible in Cygnus X-3 unless the jet is less powerful or wider.

Abstract

Jets powered by high-mass X-ray binaries must traverse the powerful wind of the companion star. We present the first global 3D simulations of jet-wind interaction in high-mass X-ray binaries. We show that the wind momentum flux intercepted by the jet can lead to significant bending of the jet and that jets propagating through a spherical wind will be bent to an asymptotic angle $\psi_{\infty}$. We derive simple expressions for $\psi_{\infty}$ as a function of jet power and wind thrust. For known wind parameters, measurements of $\psi_{\infty}$ can be used to constrain the jet power. In the case of Cygnus X-1, the lack of jet precession as a function of orbital phase observed by the VLBA can be used to put a lower limit on the jet power of $L_{\rm jet} \gtrsim 10^{36}\,{\rm ergs\,s^{-1}}$. We further discuss the case where the initial jet is inclined relative to the binary orbital axis. We also analyze the case of Cygnus X-3 and show that jet bending is likely negligible unless the jet is significantly less powerful or much wider than currently thought. Our numerical investigation is limited to isotropic stellar winds. We discuss the possible effect of wind clumping on jet-wind interaction, which are likely significant, but argue that our limits on jet power for Cygnus X-1 are likely unaffected by clumping unless the global wind mass loss rate is orders of magnitude below the commonly assumed range for Cyg X-1.