Neutrino-driven explosion of a 20 solar-mass star in three dimensions enabled by strange-quark contributions to neutrino-nucleon scattering (1504.07631v2)

Abstract: Interactions with neutrons and protons play a crucial role for the neutrino opacity of matter in the supernova core. Their current implementation in many simulation codes, however, is rather schematic and ignores not only modifications for the correlated nuclear medium of the nascent neutron star, but also free-space corrections from nucleon recoil, weak magnetism or strange quarks, which can easily add up to changes of several 10% for neutrino energies in the spectral peak. In the Garching supernova simulations with the Prometheus-Vertex code, such sophistications have been included for a long time except for the strange-quark contributions to the nucleon spin, which affect neutral-current neutrino scattering. We demonstrate on the basis of a 20 M_sun progenitor star that a moderate strangeness-dependent contribution of g_a^s = -0.2 to the axial-vector coupling constant g_a = 1.26 can turn an unsuccessful three-dimensional (3D) model into a successful explosion. Such a modification is in the direction of current experimental results and reduces the neutral-current scattering opacity of neutrons, which dominate in the medium around and above the neutrinosphere. This leads to increased luminosities and mean energies of all neutrino species and strengthens the neutrino-energy deposition in the heating layer. Higher nonradial kinetic energy in the gain layer signals enhanced buoyancy activity that enables the onset of the explosion at ~300 ms after bounce, in contrast to the model with vanishing strangeness contributions to neutrino-nucleon scattering. Our results demonstrate the close proximity to explosion of the previously published, unsuccessful 3D models of the Garching group.

Neutrino-Driven Explosion of a 20 Solar Mass Progenitor in Three Dimensions

The paper by Melson et al. focuses on the intricate aspects of neutrino interactions within the core-collapse supernovae framework. This paper employs three-dimensional (3D) simulations to explore the effects of strange-quark contributions to neutrino-nucleon scattering on the explosion dynamics of a 20 solar mass ($M_\odot$) supernova progenitor. The findings underscore the sensitivity of supernova simulations to microscale interaction parameters and emphasize how subtle changes can drastically influence macroscopic outcomes like stellar explosions.

Key Findings and Numerical Results

The pivotal result of this research is the demonstration that the inclusion of strange-quark contributions, specifically a strangeness-dependent axial-vector coupling constant $g_\mathrm{a}^\mathrm{s} = -0.2$, can transform an unsuccessful 3D supernova model into a successful one. This modification results in significant alterations to the neutral-current scattering opacity of neutrons, subsequently enhancing the neutrino luminosities and mean energies. Notably, the paper reveals that such adjustments lead to increased neutrino-energy deposition in the heating layer, bolstering the buoyancy-driven turbulence necessary for shock revival.

Quantitatively, the paper reports up to a 30% increase in the luminosities of heavy-lepton neutrinos ($\nu_x$ species) and a general rise in the mean energies across all neutrino types. The simulation indicates a pronounced increase in non-radial kinetic energy within the gain layer, which ultimately facilitates the onset of the explosion approximately 300 milliseconds after core bounce.

Implications for Supernova Modeling

The implications of this work are profound for both theoretical astrophysics and computational simulation methodologies. The paper highlights the sensitivity of supernova simulations to small-scale physical corrections, such as those accounting for strange-quark interactions. These findings suggest that refinements in neutrino interaction physics could reconcile differing results obtained across various supernova models documented in the literature. Moreover, this paper amplifies the necessity for high-fidelity physics implementations in core-collapse supernovae simulations.

Practically, the paper's outcomes could impact our understanding of nucleosynthesis and compact remnant formation scenarios. The enhanced energy deposition could influence the mass and composition of ejected material, with potential ramifications for the chemical enrichment patterns observed in the galaxy.

Future Perspectives

Looking forward, this research opens avenues for more comprehensive investigations into the neutrino-matter interactions by considering other potential sources of corrections, such as in-medium effects and detailed nucleon correlations. Fine-tuning these physics components might further clarify the conditions under which different progenitors explode or fail.

Additionally, future work should aim to confirm the robustness of these findings under varied conditions, including different progenitors and enhanced computational resolutions. Such efforts would help to solidify the theoretical framework and bolster the predictive power of supernova simulations.

In conclusion, Melson et al.'s work contributes significantly to the field of core-collapse supernova dynamics by articulating the critical effects of strange-quark contributions to neutrino scattering. It provides valuable insights into how subtle microphysical processes can tip the scales towards explosive stellar outcomes, underscoring the complex interplay between neutrino physics and multi-dimensional hydrodynamics in stellar environments.