1307.2939 (S. Rosswog et al.)

The longterm evolution of neutron star merger remnants I: the impact of r-process nucleosynthesis    [PDF]

S. Rosswog, O. Korobkin, A. Arcones, F. -K. Thielemann

We follow the longterm evolution of the dynamic ejecta of neutron star mergers for up to 100 years and over a density range of roughly 40 orders of magnitude. We include the nuclear energy input from the freshly synthesized, radioactively decaying nuclei in our simulations and study its effects on the remnant dynamics. Although the nuclear heating substantially alters the longterm evolution, we find that running nuclear networks over purely hydrodynamic simulations (i.e. without heating) yields actually acceptable nucleosynthesis results. The main dynamic effect of the radioactive heating is to quickly smooth out inhomogeneities in the initial mass distribution, subsequently the evolution proceeds self-similarly and after 100 years the remnant still carries the memory of the initial binary mass ratio. We also explore the nucleosynthetic yields for two mass ejection channels. The dynamic ejecta very robustly produce "strong" r-process elements with A>130 with a pattern that is essentially independent of the details of the merging system. From a simple model we find that neutrino-driven winds yield "weak" r-process contributions with 50View original: http://arxiv.org/abs/1307.2939