Acoustic-Powered Supernovae

Understanding how massive stars explode as core-collapse supernovae (CCSN) remains an important challenge in stellar evolution theory. When massive stars reach the end of their lives, the central iron core can no longer support the weight of the surrounding material. The iron core collapses, and at nuclear densities, the core bounces, forming a proto-neutron star (PNS). This bounce launches a shock wave; however, this shock quickly stalls due to the ram pressure of the collapsing star, energy losses due to dissociation of the nuclei, and neutrino emission. A primary challenge is understanding how the stalled shock is revived initiating the explosion that unbinds the star. The key to successful explosions is transporting energy from the hot PNS star outward to the region just behind the shock. Theory suggests that neutrinos may transport some of the required energy. Multi-dimensional simulations show that turbulent dissipation by neutrino-driven convection is significant in aiding successful explosions. Another mechanism for energy transport has recently been suggested: convection in the core may generate sound waves that would transport energy outward possibly depositing even more energy behind the shock. In this dissertation, we explore whether this acoustic power is efficient in aiding CCSN explosions. In order to model these effects, we develop the hydrodynamics code Cufe, which employs a general metric to solve the Euler equations. Through verification and validation, we show that Cufe can efficiently and accurately simulate astrophysical problems. With a systematic study of acoustic power, we execute one-dimensional and two-dimensional simulations. These simulations show that the acoustic power reduces the critical condition for explosion by at most 5%. This result is somewhat unexpected. Previous studies had assumed that acoustic power would be perfectly absorbed in the region behind the shock. On the contrary, we show that the acoustic waves are likely damped by neutrinos and are less effective than assumed in depositing energy behind the shock. In summary, neutrino heating and turbulent dissipation remain the dominant mechanisms for successful core-collapse supernova explosions.