On The Development of Multidimensional Progenitor Models For Core-collapse Supernovae

Multidimensional hydrodynamic simulations of shell convection in massive stars suggest the development of aspherical perturbations that may be amplified during iron core-collapse. These perturbations have a crucial and qualitative impact on the delayed neutrino-driven core-collapse supernova explosion mechanism by increasing the total stress behind the stalled shock. In this paper, we investigate the properties of a 15 \msun model evolved in 1-,2-, and 3-dimensions (3D) for the final $\sim$424 seconds before gravitational instability and iron core-collapse using MESA and the FLASH simulation framework. We find that just before collapse, our initially perturbed fully 3D model reaches angle-averaged convective velocity magnitudes of $\approx$ 240-260 km s$^{-1}$ in the Si- and O-shell regions with a Mach number $\approx$ 0.06. We find the bulk of the power in the O-shell resides at large scales, characterized by spherical harmonic orders ($\ell$) of 2-4, while the Si-shell shows broad spectra on smaller scales of $\ell\approx30-40$. Both convective regions show an increase in power at $\ell=5$ near collapse. We show that the 1D \texttt{MESA} model agrees with the convective velocity profile and speeds of the Si-shell when compared to our highest resolution 3D model. However, in the O-shell region, we find that \texttt{MESA} predicts speeds approximately \emph{four} times slower than all of our 3D models suggest. All eight of the multi-dimensional stellar models considered in this work are publicly available.