The ν-Process in the Light of an Improved Understanding of Supernova Neutrino Spectra

Abstract

We study the neutrino-induced production of nuclides in explosive supernova nucleosynthesis for progenitor stars with solar metallicity including neutrino nucleus reactions for all nuclei with charge numbers Z < 76 with average neutrino energies in agreement with modern Supernova simulations. Considering progenitors with initial main sequence masses between 13 M and 30 M , we find a significant production of 11 B, 138 La, and 180 Ta by neutrino nucleosynthesis, despite the significantly reduced neutrino energies. The production of 19 F turns out to be more sensitive to the progenitor mass and structure than to the ν process. With our complete set of cross sections we have identified effects of the ν process on several stable nuclei including 33 S, 40 Ar, 41 K, 59 Co, and 113 In at the 10% level. Neutrino-induced reactions contribute to a similar extent to the production of radioactive 26 Al and increase the yield of 22 Na by 50%. Future γ ray astronomy missions may reach the precision at which the contribution from the ν process becomes relevant. We find that the production of 22 Na by the ν process could explain the Ne-E(L) component of meteoritic graphite grains. The ν process enhances the yield of 36 Cl and we point out that the resulting 36 Cl/ 35 Cl ratio is in agreement with the values infrerred for the early solar system. Our extended set of neutrino-nucleus interactions also allows us to exclude any further effects of the ν process on stable nuclei and to quantify the effects on numerous, hitherto unconsidered radioactive nuclei, e.g., 36 Cl, 72 As, 84 Rb, and 88 Y.

The ν-process with Fully Time-dependent Supernova Neutrino Emission Spectra

“…Figure 3 shows the mass fraction profiles of the light nuclides 11 B and 7 Li as obtained in the nucleosynthesis studies with our different approaches (see Table 1 for an overview of the approaches). Additionally, we give the results for the same stellar model presented by Sieverding et al (2018), which, as discussed above, are close to those obtained in our Approach 3. Both nuclides are produced in the ν process by the reaction chains 3 H(α, γ) 7 Li(α, γ) 11 B and 3 He(α, γ) 7 Be(α, γ) 11 C following the neutrino-induced reactions on 4 He that produce 3 He and 3 H. 11 C is radioactive and decays to 11 B with a halflife of 20 min.…”

“…For Approach 2 we obtain E ν e = 10.9 MeV, Eν e = 12.6 MeV, E ν x = 11.7 MeV and Eν x = 12.6 MeV. These are effectively the same average values as the set of "low" neutrino energies discussed and adopted in Sieverding et al (2018) except for the electron neutrinos.…”

“…A detailed discussion can also be found in Sieverding et al (2018). Due to the inclusion of the burst and accretion phases, the electron neutrinos have a higher average energy in our Approach 2 compared to Approach 3 and to the values adopted by Sieverding et al (2018). As a consequence, the production of 11 B in the C shell is increased, because charged-current reactions contribute almost half to the 11 B synthesis in this layer.…”

“…An important contribution to 11 B also comes from the O/C shell in which neutrino-induced spallation of 12 C produces 11 C and 11 B directly. A detailed discussion can also be found in Sieverding et al (2018). Due to the inclusion of the burst and accretion phases, the electron neutrinos have a higher average energy in our Approach 2 compared to Approach 3 and to the values adopted by Sieverding et al (2018).…”

Astronuclear Physics: A tale of the atomic nuclei in the skies

“…This evaluation is done in the framework of the RPA (e.g. [238] for a recent application) or shell models. Many interesting and complicated problems are also raised by various aspects of nucleon correlations and spin fluctuations in neutrino scattering at high densities [239].…”