Speaker
Prof.
Taka Kajino
(National Astronomical Observatory of Japan, The University of Tokyo)
Description
Core-collapse supernovae (both magneto-hydrodynamic jet supernovae; MHD Jet-SNe, and
neutrino-driven wind supernovae; n-SNe), and binary neutron-star mergers (NSMs) are viable
astrophysical sites for r-process elements [1]. The MHD Jet-SNe explain the “universality” in the
observed abundance pattern in metal poor stars, while NSMs could not contribute to the early Galaxy
for cosmologically long merging time-scale for very slow GW radiation. The NSM is still an
important nucleosynthetic site for the solar-system r-process abundances [2], suggesting a possible
site for fission recycling r-process [3]. The origin of heavy nuclei has not been clearly understood
although sixty years have already passed since B2FH (1957). We will discuss that the
neutrino-induced nucleosynthesis takes the significant keys to solve this long standing question.
Nucleosynthesis of light-to-heavy mass nuclei like 7
Li and 11B and intermediate-to-heavy mass
nuclei like 92Nb, 98Tc, 138La, 180Ta and r-process elements is strongly affected by the neutrino flavor
oscillations in the n-SNe [4]. These effects are less pronounced in MHD Jet-SNe and NSMs for
faster expansion time scale than the neutrino-nucleus interaction time scale. We will first discuss
the sensitivity of these nuclear abundances to the neutrino parameters of each species ne, nμ, nt, or
their anti-particles. We then discuss how to constrain the neutrino mass hierarchy through the
MSW effects [5].
The elements whose masses are in the range of 80-100 have several possible nuclear reactions
such as r-, s-, rp-, g-, np-processes, etc. Although the n-SN is presumed to be the robust
astrophysical site of the 1st r-process abundance-peak elements like As-Se-Br, neutron-rich condition
(Ye < 0.5) suitable for a successful r-process is sometimes broken, depending on the neutrino
luminosities and spectra. When one takes account of collective neutrino oscillations, n-driven
winds could turn into proton-rich (Ye > 0.5). We will, secondly, discuss the effects of collective
neutrino oscillations on the vp-process nucleosynthesis. We propose that the proton-rich outflows
from the n-SNe could be the astrophysical site for the production of 92Mo, 96Ru and other abundant
p-nuclei [6].
[1] T. Kajino & G. J. Mathews, Rep. Prog. Phys. 80 (2017), 084901.
[2] Y. Hirai, Y. Ishimaru, T. R. Saitoh et al. with T. Kajino, ApJ 814 (2015), 41; Mon. Not. Roy.
Astron. Soc. 466 (2017), 2472-2487.
[3] S. Shibagaki, T. Kajino, G. J. Mathews et al., ApJ 816 (2016), 79.
[4] T. Kajino, G. J. Mathews & T. Hayakawa, J. Phys. G41 (2014), 044007.
[5] G. J. Mathews, T. Kajino, W. Aoki & W. Fujiya, Phys. Rev. D85 (2012), 105023; T. Suzuki & T.
Kajino, J. Phys. G40 (2013), 083101.
[6] H. Sasaki, T. Kajino, T. Takiwaki et al., Phys. Rev. D96 (2017), 043013.
Primary author
Prof.
Taka Kajino
(National Astronomical Observatory of Japan, The University of Tokyo)
