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Asymmetric Supernovae: New Physics and Implications for Nucleosynthesis J. Craig Wheeler Abstract We have known for decades that compact remnants of supernovae in the guise of pulsars involve rotation and magnetic fields at a fundamental level. What has not been clear is whether or not rotation and magnetic fields play a critical role in the formation of the supernova explosion itself. New observations, especially systematic spectropolarimetry, have brought new perspective to this issue. To date, all core collapse supernovae with adequate data are observed to be significantly polarized and hence substantially asymmetric. Many show a single dominant axis of orientation: they are substantially bi-polar. The observed increase in asymmetry with depth in the ejecta implies that it is the fundamental mechanism of the explosion itself that is asymmetric. Simulations have shown that this asymmetry could plausibly be generated by sufficiently energetic jets originating in core collapse. While it may be possible to generate strongly asymmetric flows by asymmetric neutrino deposition engendered by rotation alone, physical considerations suggest that the strong differential rotation that is intrinsic to core collapse must also generate associated magnetic fields. In particular, the magneto-rotational instability coupled with modern dynamo theory suggests that toroidal fields of order 1015 Gauss will be generated in tens of milliseconds after core bounce. The open issues are whether or not these fields will produce dynamically-significant, jet-like flows and how to make connections to pulsars, magnetars and, perhaps, gamma-ray bursts. The strong asymmetries and circulation flows are likely to affect the nucleosynthesis. Polarization has also shown that Type Ia supernovae are mildly asymmetric in a manner that again suggests that rotation of the progenitor white dwarf may be involved. These results suggest that asymmetric luminosity may contribute to the current dispersion in light curve peak/decline relations used to measure the dark energy with these supernovae. Suitable observations may allow this dispersion to be calibrated out. |