John M. Blondin NC State University

1. Discovering the Complexity of Supernovae through 3D Simulations John M. Blondin NC State University

3. We begin our story in 1572… ``On the 11th day of November in the evening after sunset, I was contemplating the stars in a clear sky. I noticed that a new and unusual star, surpassing the other stars in brilliancy, was shining almost directly above my head.’’ -- Tycho Brahe

4. Again in 1604… Johannes Kepler observed a “stella nova” that became as bright as Jupiter, but faded away after a couple months.

5. For 400 years there has not been a supernova in our Galaxy … we are still waiting! But, in a nearby galaxy not long ago (February 1987)…

6. We can learn even more by looking at what is left hundreds of years later.

7. Remnants of Supernova Explosions Relic Blastwave Spinning Neutron Star

8. The iron core contains about 3 times the mass of our Sun, but it is roughly the size of our Earth. This iron core collapses under its own weight until it is small enough to fit inside Puget Sound. At this point the core is as dense as the nucleus of an atom and it cannot compress any further. The rest of the star ‘bounces’ off this hard core and explodes off into space???

9. It all starts with core collapse…

10. The Supernova story has a long history of computational physics… • 1966 Colgate and White Neutrino-Driven prompt explosion • 1985 Bethe and Wilson Shock reheating via neutrino energy deposition • 1992 Herant, Benz, and Colgate Convective instability above neutrino-sphere

11. Anatomy of a Core-Collapse Supernova The last decade has seen a great deal of interest in multidimensional effects: Convection with the proto-neutron star Neutrino-driven convection below the stalled shock Instability of the stalled shock All of these may operate together!

12. First generation of 2D SN models hinted at a low-order asymmetry in the shock wave at late times (100’s of msec after bounce). Burrows, Hayes & Fryxell 1995

13. REU Students, Summer 2000 Christine DeMarino Brett Unks Dana Paquin

14. To investigate the dynamics of the stalled supernova shock, we consider an idealized problem:

15. In One Dimension: Analytical: Houck & Chevalier (1992) presented a linear stability analysis. Numerical: Blondin et al. (2003) perturb SAS and watch the evolution. Pressure Perturbation Radius Time ->

16. SN Code Verification Houck and Chevalier 1992 Blondin and Mezzacappa 2005 This post-bounce model provides an opportunity to verify supernova codes against the results of a linear perturbation analysis.

17. Spherical Accretion Shock Instability Blondin, Mezzacappa, DeMarino 2003, ApJ, 584, 971

18. The SASI is a global acoustic mode: The spherical accretion shock acts as an acoustic cavity, with a trapped standing wave growing exponentially with time.

20. Must move to 3D! This initial SASI discovery with axisymmetric 2D simulations pointed to the obvious need for models in full 3D.

21. Hurdles for Large-Scale 3D Not a problem Simulation code Floating points Data output Data transport Visualization and analysis Thank you DOE It works Does not work I can’t see!

22. First Results: SASI Exists in 3D • 3D Cartesian grid • 100 Million zones • 100’s of processors • 100’s of GB in full run Without interactive access to the data, this was science in the dark!

23. Shared file system Cray X1 Billion-cell simulation in 30 hours generates 4 terabytes Visualization platform Science Begins with Data Scientific discovery is done with interactive access to data. • Must have interactive access on a large-memory computer for analysis and visualization. • Must have high bandwidth in accessing the data. • Must have sufficient storage to hold data for weeks/months.

24. Interactive Visualization of TB Datasets A commodity linux cluster provides all the ‘must haves.’ Data is sliced into slabs and stored on local disks on the cluster nodes. EnSight Gold provides an easy visualization solution, including remote client-server operation and collaboration.

36. SASI A non-rotating, spherically symmetric progenitor star can leave behind a neutron star spinning with a period of tens of milliseconds.

37. A Million Second Chandra View of Cassiopeia A Hwang et. al. 2004 “These are most likely due to jets of ejecta as opposed to cavities in the circumstellar medium, since we can reject simple models for the latter.”

38. If the progenitor star possessed an asymmetric stellar wind (e.g., due to rotation), the supernova remnant driven into this relic wind would reflect the asymmetry of the wind. Forward shock Reverse shock In this 2D simulation, the density in the progenitor wind is four times denser in the equatorial plane than at the poles.

40. Never believe a jet in 2D… equator pole q radius equator

42. A “Jet” from a Spherical Supernova Fast Ejecta Shocked Ejecta Leading Shockwave