Title: Evolution of r-process elements: whole isotopic abundance pattern from multi astrophysical sites
Yuta Yamazaki
Abstract:
R-process is a neutron capture process which produce a half of heavy elements in the universe. However, its detailed process is still not clear since r-process proceed by capturing neutrons very rapidly. Its astrophysical site(s) is also under debate although some candidates, such as type II supernova or neutron star merger, have been considered as possible sites for many years. To resolve this open question, many calculations of galactic chemical evolution have been performed. In those previous studies, time evolution of Europium, a representative r-process element, have been discussed by considering different time-varying contribution from supernova and neutron star merger. Both of the observations and theoretical calculations, however, have such a large uncertainty that the debate has not been settled yet. In this study, we focused on the deference in abundance pattern found in deferent astrophysical sites. R-process nucleosynthesis is affected by neutron richness, in particular, yields of elements heavier than lanthanoids are strongly dependent on its environment. We calculated the abundance pattern over the whole range of r-process elements as a function of time by using a one-zone galactic chemical evolution model. Contribution from all possible astrophysical sites are taken into account. Results are evaluated by the observed abundance of metal-poor stars in the Milky Way. In this talk, suggestions about r-process nucleosynthesis from our theoretical calculation will be discussed on the basis of observational data. I will also talk about some future prospects of r-process studies with next-generation telescopes.