Progenitor-Dependent Explosion Dynamics in Self-Consistent, Axisymmetric Simulations of Neutrino-Driven Core-Collapse Supernovae

We present self-consistent, axisymmetric core-collapse supernova simulations performed with the Prometheus-Vertex code for 18 pre-supernova models in the range of 11–28 M ⊙, including progenitors recently investigated by other groups. All models develop explosions, but depending on the progenitor structure, they can be divided into two classes. With a steep density decline at the Si/Si–O interface, the arrival of this interface at the shock front leads to a sudden drop of the mass-accretion rate, triggering a rapid approach to explosion. With a more gradually decreasing accretion rate, it takes longer for the neutrino heating to overcome the accretion ram pressure and explosions set in later. Early explosions are facilitated by high mass-accretion rates after bounce and correspondingly high neutrino luminosities combined with a pronounced drop of the accretion rate and ram pressure at the Si/Si–O interface. Because of rapidly shrinking neutron star radii and receding shock fronts after the passage through their maxima, our models exhibit short advection timescales, which favor the efficient growth of the standing accretion-shock instability. The latter plays a supportive role at least for the initiation of the re-expansion of the stalled shock before runaway. Taking into account the effects of turbulent pressure in the gain layer, we derive a generalized condition for the critical neutrino luminosity that captures the explosion behavior of all models very well. We validate the robustness of our findings by testing the influence of stochasticity, numerical resolution, and approximations in some aspects of the microphysics.

Self-perceptions of the role of the planner

The role of the planning practitioner has received considerable attention in a diverse range of theoretical and empirical debates within the broad spectrum of planning scholarship from normative debates surrounding the planner's role in society, to more empirical investigations into the skills, attributes, and evolving nature of planning practitioners. Fundamental questions surrounding the role and purpose of planners have also entered into more mainstream discussions as the democratic nature of the planning system has been consistently undermined by allegations of misconduct, corruption, and incompetence. Despite the broad range of literature and debate which centres on the role of the planner, relatively few studies have explored the views of planning practitioners themselves, making it difficult to judge whether the ideas of planning academics are actually shared by those in the field. In this paper we seek to address this particular gap and argue that such insights are critical in determining the extent to which planning practitioners serve to challenge, maintain, or reinforce existing power imbalances in the planning system. The methodology consists of a series of qualitative interviews with twenty local authority planners working throughout the Greater Dublin Area, Ireland. The results suggest that planners' self-perceptions of their role tend to reflect traditional pluralist and managerialist perspectives. More broadly, the results suggest that the role orientations of contemporary planners are being shaped by dominant discourses in current planning ideology — namely, collaborative and participatory approaches