Spiral shocks in three-dimensional accretion discs

We have performed three-dimensional (3D) numerical simulations of accretion discs in a close binary system using the smoothed particle hydrodynamics (SPH) method. Our results show that, contrary to previous claims, 3D discs do exist even when the specific heat ratio of the gas is as large as gamma=1.2. Although the disc is clearly more spread in the z direction in this case than it is for the quasi-isothermal one, the disc height is compatible with the hydrostatic balance equation. Our numerical simulations with gamma=1.2 also demonstrate that spiral shocks exist in 3D discs. These results therefore confirm previous 2D simulations.