The Spherical Accretion Shock Instability, or SASI, is a hydrodynamic instability discovered by Blondin, Mezzacappa & DeMarino (2003) in their numerical study of the stalled accretion shock in core-collapse supernovae. In 2D axisymmetry this instability drives an initially spherical accretion shock into a 'sloshing' mode in which it oscillates up and down the symmetry axis. This phenomenon has subsequently been seen in a variety of supernova simulations by numerous authors.
Stellar Rotation was included in subsequent 2D simulations (with progenitor spin necessarily about the symmetry axis), which showed a mild influence of the rotation on the linear growth rate of the SASI. The effect of rotation is much more pronounced, however, on non-axisymmetric modes which cannot exist in 2D axisymmetric simulations.
Non-Axisymmetric Modes were first seen in 3D simulations of a stationary spherical accretion shock (Blondin & Mezzacappa 2007). That work also demonstrated that a moderate rotation in the progenitor star led to a much quicker dominance of the spiral SASI. These non-axisymmetric modes (the spiral patterns on the left) were studied in detail by Blondin & Shaw (2007), who used 2D simulations in the equatorial plane of a spherical grid to quantify the growth rates and verify the linear nature of these 'm' modes. They also showed that, in this restricted 2D geometry, the axisymmetric mode is a linear combination of two oppositely-directed spiral waves.
The goal of this work is to quantify the effect of progenitor rotation on the linear growth of the SASI: How much faster does the SASI grow if the stellar core is rotating?
