Analytic Approach to the Stability of Standing Accretion Shocks: Application to Core‐Collapse Supernovae

We explore an analytic model of the accretion shock in the post bounce phaseof a core-collapse supernova explosion. We find growing oscillations of theshock in the l=1 and l=2 modes, in agreement with a variety of existingnumerical simulations. For modest values of the ratio of the outer accretionshock to that of the inner boundary to the shocked flow, the instabilityappears to derive from the growth of trapped sound waves, whereas at highervalues, postshock advection clearly plays a role. Thus the model described heremay relate to the different mechanisms of instability recently advocated byBlondin & Mezzacappa, and by Foglizzo and collaborators.Comment: 23 pages, 3 figures, accepted by Ap