Stellar Wind Turbulence and its Effects on Hoyle-Lyttleton Accretion

Gravitational accretion from a stellar wind powers a subset of x-ray binaries containing a high-mass star and a neutron star or black hole companion. The dynamics of this wind accretion has been extensively studied using hydrodynamic simulations, always under the assumption of smooth upstream flow. We know winds from hot stars to be clumpy which can be expected to lead to post shock turbulence at the accretor. Using three dimensional hydrodynamics simulations, we investigate the effects of turbulent flow on Hoyle-Lyttleton accretion. Each run is evolved with a smooth upstream wind to form a steady, smooth bow shock. Once steady state is reached we begin to add in wind clumps upstream and evolve in order to produce turbulent flow. The wind clumps are simulated using a perlin algorithm that produces randomized density clumps with a prescribed wavenumber and density contrast. We quantify the effects of the post shock turbulence on the efficiency of the mass accretion rate, the variation in accreted angular momentum, and the size and shape of the bow shock.