报告题目：Supernova Neutrino Oscillation and the Origin of Heavy Elements
报告人：Taka Kajino (NAO of Japan, University of Tokyo)
报告时间：2016年10月27日 星期四 16:00
Dr. Kajino obtained his Ph.D. degree in 1984 from The University of Tokyo. From 1984 to 1993, he was an assistant professor at Tokyo Metropolitan University. Since 1993/1994, he has been a professor of Theoretical Astrophysics at National Astronomical Observatory of Japan and a professor of Astronomy at the University of Tokyo. In 2004, he was elected a Fellow of the American Physical Society (APS) and in 2016 he was awarded “the Thousand Talents Plan” professorship. He has published about 200 refereed articles.
Energetic supernova (SN) neutrinos are subject to flavor oscillation due to the MSW effect which depends on still unknown neutrino-mass "hierarchy". We first discuss how to constrain the "hierarchy" by predicting energy spectra of relic SN neutrinos which are expected in Hyper-Kamiokande water-Cerenkov detector.We secondly discuss SN neutrino nucleosynthesis in order to determine the "hierarchy" more precisely.Element genesis in SNe of several light-to-intermediate mass nuclei are known to be affected by the MSW effect, which depends on the synthesis sites. We will propose a new nucleosynthetic method to determine the "hierarchy" and show successful example of the cosmic clock. We thirdly discuss a recent debate of unidentified origin of the r-process elements like U and Th, i.e. rotational driven magneto-hydrodynamic jet SN (MHD-jet SN) vs. binary neutron star merger (NSM). Spectroscopic observations of early generations of halo stars (EMP stars) in the Milky Way show "universality" that the elemental abundance pattern in the EMP stars as quite similar to the solar-system.The MHD-jet SN model can naturally explain the "universality", while the binary NSMs could't contribute in the early Galaxy because of their cosmologically long merging time scale for slow GW radiation ("time-scale problem"). We try to solve this problem by carrying out large scale numerical simulations of Galactic chemo-dynamical evolution including SN feedback. We will then propose a best model to solve the mystery of the origin of heavy r-process elements.