L. Huther

Charged-Current Weak Interaction Processes in Hot and Dense Matter and its Impact on the Spectra of Neutrinos Emitted from Protoneutron Star Cooling

We perform three-flavor Boltzmann neutrino transport radiation hydrodynamics simulations covering a period of 3 s after the formation of a protoneutron star in a core-collapse supernova explosion. Our results show that a treatment of charged-current neutrino interactions in hot and dense matter as suggested by Reddy et al. [Phys. Rev. D 58, 013009 (1998)] has a strong impact on the luminosities and spectra of the emitted neutrinos. When compared with simulations that neglect mean-field effects on the neutrino opacities, we find that the luminosities of all neutrino flavors are reduced while the spectral differences between electron neutrinos and antineutrinos are increased. Their magnitude depends on the equation of state and in particular on the symmetry energy at subnuclear densities. These modifications reduce the proton-to-nucleon ratio of the outflow, increasing slightly their entropy. They are expected to have a substantial impact on nucleosynthesis in neutrino-driven winds, even though they do not result in conditions that favor an r process. Contrary to previous findings, our results show that the spectra of electron neutrinos remain substantially different from those of other (anti)neutrino flavors during the entire deleptonization phase of the protoneutron star. The obtained luminosity and spectral changes are also expected to have important consequences for neutrino flavor oscillations and neutrino detection on Earth.

Large-scale evaluation of β-decay rates of r-process nuclei with the inclusion of first-forbidden transitions

Background: r-process nucleosynthesis models rely, by necessity, on nuclear structure models for input. Particularly important are β-decay half-lives of neutron-rich nuclei. At present only a single systematic calculation exists that provides values for all relevant nuclei making it difficult to test the sensitivity of nucleosynthesis models to this input. Additionally, even though there are indications that their contribution may be significant, the impact of first-forbidden transitions on decay rates has not been systematically studied within a consistent model. Purpose: Our goal is to provide a table of β-decay half-lives and β-delayed neutron emission probabilities, including first-forbidden transitions, calculated within a fully self-consistent microscopic theoretical framework. The results are used in an r-process nucleosynthesis calculation to asses the sensitivity of heavy element nucleosynthesis to weak interaction reaction rates. Method: We use a fully self-consistent covariant density functional theory (CDFT) framework. The ground state of all nuclei is calculated with the relativistic Hartree-Bogoliubov (RHB) model, and excited states are obtained within the proton-neutron relativistic quasiparticle random phase approximation (pn-RQRPA). Results: The β-decay half-lives, β-delayed neutron emission probabilities, and the average number of emitted neutrons have been calculated for 5409 nuclei in the neutron-rich region of the nuclear chart. We observe a significant contribution of the first-forbidden transitions to the total decay rate in nuclei far from the valley of stability. The experimental half-lives are in general well reproduced for even-even, odd-A, and odd-odd nuclei, in particular for short-lived nuclei. The resulting data table is included with the article as Supplemental Material. Conclusions: In certain regions of the nuclear chart, first-forbidden transitions constitute a large fraction of the total decay rate and must be taken into account consistently in modern evaluations of half-lives. Both the β-decay half-lives and β-delayed neutron emission probabilities have a noticeable impact on the results of heavy element nucleosynthesis models.

Impact of active-sterile neutrino mixing on supernova explosion and nucleosynthesis

We show that for the active-sterile flavor mixing parameters suggested by the reactor neutrino anomaly, substantial νe-νs ande-¯s conversion occurs in regions with an electron fraction of ≈1=3 near the core of an 8.8M⊙ electron-capture supernova. We explicitly include the feedback of such conversion on the evolution of the electron fraction in supernova ejecta. Compared to the case without such conversion, the neutron richness of the ejecta is enhanced to allow production of elements from Sr, Y, and Zr up to Cd in broad agreement with observations of the metal-poor star HD 122563 for a wide range of mixing parameters. Active-sterile flavor conversion can also strongly suppress neutrino heating at times when it is important for the revival of the shock. Our results suggest that simulations of a supernova explosion and the associated nucleosynthesis may be used to constrain active-sterile mixing parameters in combination with neutrino experiments and cosmological considerations.

Effects of neutrino oscillations on nucleosynthesis and neutrino signals for an 18 M supernova model

In this paper, we explore the effects of neutrino flavor oscillations on supernova nucleosynthesis and on the neutrino signals. Our study is based on detailed information about the neutrino spectra and their time evolution from a spherically symmetric supernova model for an

Supernova neutrinos and nucleosynthesis

18{M}_{\ensuremath{\bigodot}}

Early protoneutron star deleptonization - consistent modeling of weak processes and equation of state

progenitor. We find that collective neutrino oscillations are not only sensitive to the detailed neutrino energy and angular distributions at emission, but also to the time evolution of both the neutrino spectra and the electron density profile. We apply the results of neutrino oscillations to study the impact on supernova nucleosynthesis and on the neutrino signals from a Galactic supernova. We show that in our supernova model, collective neutrino oscillations enhance the production of rare isotopes

Role of neutrinos for the nucleosynthesis of heavy elements beyond iron in explosions of massive stars

^{138}\mathrm{La}

Beta decay rates of neutron-rich nuclei

and

Weak interaction processes in astrophysics: neutrino winds from proto-neutron stars

^{180}\mathrm{Ta}

Stellar enhancement factors in a parity dependent approach

but have little impact on the