Speaker
Description
The origin of heavy elements via the r-process remains a frontier in nuclear astrophysics. While neutron star mergers (NSMs) are confirmed sites, collapsars and magnetohydrodynamically driven jets (MHDJs) offer unique environments due to their distinct jet dynamics.
We discover for the first time that fission neutrons released after the r-process freeze-out can induce secondary i- and s-processes exclusively in collapsar jets. This originates from the synergy of an extremely neutron-rich environment and jet deceleration, which maintains the required late-time neutron density. To quantify these contributions, we propose a new theoretical decomposition method to separate the contributions of r-, i-, and s-processes. Sensitivity analyses reveal that specific neutron-capture reactions, such as Yb175(n,g)Yb176 and Er169(n,g)Er170, significantly impact rare-earth element synthesis, pointing to future experimental targets. Additionally, elevated [Tm/Eu] and [Lu/Eu] ratios are identified as potential observational indicators for collapsars.
Furthermore, we establish a theoretical framework for late-time jet propagation by considering the collision between the jets and the ambient medium, deriving a density evolution corrected for jet deceleration and mass accumulation. This work bridges hydrodynamic simulations, nuclear physics, and astronomical observations, enriching our understanding of heavy element nucleosynthesis.
| Category | Theory |
|---|