Neutrino Signal of Electron-Capture Supernovae from Core Collapse to Cooling

An 8.8 solar mass electron-capture supernova (SN) was simulated in spherical symmetry consistently from collapse through explosion to nearly complete deleptonization of the forming neutron star. The evolution time of about 9 s is short because of nucleon-nucleon correlations in the neutrino opacities. After a brief phase of accretion-enhanced luminosities (~200 ms), luminosity equipartition among all species becomes almost perfect and the spectra of electron antineutrinos and muon/tau antineutrinos very similar. We discuss consequences for the neutrino-driven wind as a nucleosynthesis site and for flavor oscillations of SN neutrinos.Comment: 4 pages, 4 eps figures; published as Physical Review Letters, vol. 104, Issue 25, id. 25110

Impact of eV-mass sterile neutrinos on neutrino-driven supernova outflows

Motivated by recent hints for sterile neutrinos from the reactor anomaly, we study active-sterile conversions in a three-flavor scenario (2 active + 1 sterile families) for three different representative times during the neutrino-cooling evolution of the proto-neutron star born in an electron-capture supernova. In our "early model" (0.5 s post bounce), the nu_e-nu_s MSW effect driven by Delta m^2=2.35 eV^2 is dominated by ordinary matter and leads to a complete nu_e-nu_s swap with little or no trace of collective flavor oscillations. In our "intermediate" (2.9 s p.b.) and "late models" (6.5 s p.b.), neutrinos themselves significantly modify the nu_e-nu_s matter effect, and, in particular in the late model, nu-nu refraction strongly reduces the matter effect, largely suppressing the overall nu_e-nu_s MSW conversion. This phenomenon has not been reported in previous studies of active-sterile supernova neutrino oscillations. We always include the feedback effect on the electron fraction Y_e due to neutrino oscillations. In all examples, Y_e is reduced and therefore the presence of sterile neutrinos can affect the conditions for heavy-element formation in the supernova ejecta, even if probably not enabling the r-process in the investigated outflows of an electron-capture supernova. The impact of neutrino-neutrino refraction is strong but complicated, leaving open the possibility that with a more complete treatment, or for other supernova models, active-sterile neutrino oscillations could generate conditions suitable for the r-process.Comment: 23 pages, including 14 figures and 2 tables (minor changes in the text). Matches published version in JCA

Metric-like Lagrangian Formulations for Higher-Spin Fields of Mixed Symmetry

We review the structure of local Lagrangians and field equations for free bosonic and fermionic gauge fields of mixed symmetry in flat space. These are first presented in a constrained setting extending the metric formulation of linearized gravity, and then the ($\gamma$-)trace constraints on fields and gauge parameters are eliminated via the introduction of auxiliary fields. We also display the emergence of Weyl-like symmetries in particular classes of models in low space-time dimensions.Comment: 136 pages, LaTeX. References added. Final version to appear in La Rivista del Nuovo Cimento

Effect of collective neutrino flavor oscillations on vp-process nucleosynthesis

The vp process is a primary nucleosynthesis process which occurs in core collapse supernovae. An essential role in this process is being played by electron antineutrinos. They generate, by absorption on protons, a supply of neutrons which, by (n,p) reactions, allow to overcome waiting point nuclei with rather long beta-decay and proton-capture lifetimes. The synthesis of heavy elements by the vp process depends sensitively on the \bar{\nu}_e luminosity and spectrum. As has been shown recently, the latter are affected by collective neutrino flavor oscillations which can swap the \bar{\nu}_e and \bar{\nu}_{\mu,\tau} spectra above a certain split energy. Assuming such a swap scenario, we have studied the impact of collective neutrino flavor oscillations on the vp-process nucleosynthesis. Our results show that the production of light p-nuclei up to mass number A=108 is very sensitive to collective neutrino oscillations.Comment: 4 pages, 3 figures, submitted to Physics Letters

Have Superheavy Elements been Produced in Nature?

We discuss the possibility whether superheavy elements can be produced in Nature by the astrophysical rapid neutron capture process. To this end we have performed fully dynamical network r-process calculations assuming an environment with neutron-to-seed ratio large enough to produce superheavy nuclei. Our calculations include two sets of nuclear masses and fission barriers and include all possible fission channels and the associated fission yield distributions. Our calculations produce superheavy nuclei with A ~ 300 that however decay on timescales of days.Comment: 12 pages, 11 figure