6th International Conference on Collective Motion in Nuclei under Extreme Conditions (COMEX6)

Impact of Neutron Star Merger and Supernova Nucleosynthesis on the Element Genesis and Neutrino Physics

Not scheduled

30m

Protea Hotel Fire & Ice

Invited Talk Invited Talk

Speaker

Taka Kajino (Being University/NAOJ/University of Tokyo)

Description

GW170817/SSS17a was an event of the century that opened a new window to
multi-messenger astronomy and nuclear astrophysics. Optical and near-infrared emissions
among many other observables suggest that their total energy release is consistent with
radiative decays of r-process nuclei predicted theoretically although no specific r-process
element was identified. Core-collapse supernovae (both MHD Jet-SNe and ν-SNe) are
viable candidates for the r-process. MHD Jet-SNe explain the “universality” in the
observed elemental r-process abundance pattern in metal poor stars. Neutron star merger
(NSM), on the other hand, could not contribute to the early Galaxy for cosmologically long
merging time-scale for slow GW radiation. Nevertheless, NSM is still a possible
explanation for the solar-system r-process abundance. We propose a novel solution to this
twisted problem by carrying out NSM and SN r-process nucleosynthesis calculations with
Galactic chemo-dynamical evolution [1-3].
We also discuss the impact of SN nucleosynthesis on the physics of neutrino
oscillations. The elements at A = 80-100 originate from many processes such as r-, s-, rp-,
γ-, ν-, νp-processes [4,5]. We find that νp-process operates strongly with amounts of free
neutrons being supplied even on proton-rich (Ye > 0.5) condition via p(ν, e+)n reactions
when one takes account of the effects of collective neutrino oscillations [6]. Reaction flows
can reach the production of abundant p-nuclei 94Mo, 96Ru, etc. This nucleosynthetic method
turns out to be a unique probe indicating still unknown neutrino-mass hierarchy.
[1] S. Shibagaki, T. Kajino, G. J. Mathews et al., ApJ 816 (2016), 79.
[2] T. Kajino & G. J. Mathews, Rep. Prog. Phys. 80 (2017), 084901.
[3] Y. Hirai, T. Kajino et al., ApJ 814 (2015), 41; MNRAS 466 (2017), 2472-2487.
[4] T. Kajino, G. J. Mathews & T. Hayakawa, J. Phys. G41 (2014), 044007.
[5] T. Hayakawa, T. Kajino et al., Phys. Rev. Lett. (2018), in press.
[6] H. Sasaki, T. Kajino, T. Takiwaki et al., Phys. Rev. D96 (2017), 043013.