Toward a Standard Model of Core Collapse Supernovae

Beginning with the first numerical simulations conducted by Colgate and White[1], three decades of supernova modeling have established a basic supernova paradigm. The supernova shock wave—formed when the iron core of a massive star collapses gravitationally and rebounds as the core matter exceeds nuclear densities and becomes incompressible—stalls in the iron core as a result of enervating losses to nuclear dissociation and neutrinos. The failure of this “prompt” supernova mechanism sets the stage for a “delayed” mechanism, whereby the shock is reenergized by the intense neutrino flux emerging from the neutrinospheres carrying off the binding energy of the proto-neutron star[2,3]. This heating is mediated primarily by the absorption of electron neutrinos and antineutrinos on the dissociation-liberated nucleons behind the shock. This past decade has also seen the emergence of multidimensional supernova models, which have investigated the role convection, rotation, and magnetic fields may play in the explosion [4–10], in some cases invoking new explosion paradigms. Although a plausible framework is now in place, fundamental questions about the explosion mechanism remain: Is there more than one mechanism? For example, are some core collapse supernovae neutrino driven while others driven by magnetohydrodynamic jets? Is there one mechanism for one class of massive stars—e.g., stars with progenitor masses between 10 and 20 M —and another for another class of massive stars—e.g., more massive progenitors? Or is the mechanism tailored to each progenitor? For neutrinodriven supernovae, is the neutrino heating sufficient, or are multidimensional effects such as convection and rotation necessary? In addition, any “standard model” for core collapse supernovae must reproduce observed supernova phenomenology, such as neutron star kicks[11] and the polarization of supernova emitted light[12]. To answer these questions and to develop a “standard model,” simulations in one, two, and three dimensions must be performed and coordinated.