Speaker
Description
The origin of the heaviest elements is still a matter of debate. For the rapid neutron
capture process (“r-process”), multiple sites have been proposed, e.g., neutron star
mergers and (sub-classes) of supernovae. R-process elements have been measured in
metal-poor halo stars. Galactic archaeology studies show that the r-process abundances
among these stars vary by over two orders of magnitude. On the other hand, abundances
in stars in the Galactic disk do not differ greatly. This leads to two major open questions:
1. What is the reason for such a huge abundance scatter of r-process elements in
the early Galaxy?
2. While the large scatter at low metallicities might point to a rare production site,
why is there barely any scatter at Solar metallicities?
We use the high resolution ((20 pc)^3 /cell) inhomogeneous Galactic chemical evolution
tool “ICE” to study the role of the contributing sources of r-process elements. Our main
findings are that additionally to neutron star mergers, a second, early acting site is
necessary. We assume “magnetorotationally driven supernovae” can act as this additional
and earlier r-process site and conclude that our simulations with an adequate combination
of these two sites successfully reproduce the observed r-process elemental abundances in
the Galactic halo. Finally, we discuss the potential role of neutron star-black hole mergers
as alternative earlier r-process site.
| Keywords | Nucleosynthesis |
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