Actinide-boosting r Process in Black Hole-Neutron Star Merger Ejecta

Fuente: arXiv
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Main Authors: Wanajo, Shinya, Fujibayashi, Sho, Hayashi, Kota, Kiuchi, Kenta, Sekiguchi, Yuichiro, Shibata, Masaru
Format: Preprint
Published: 2022
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author Wanajo, Shinya
Fujibayashi, Sho
Hayashi, Kota
Kiuchi, Kenta
Sekiguchi, Yuichiro
Shibata, Masaru
author_facet Wanajo, Shinya
Fujibayashi, Sho
Hayashi, Kota
Kiuchi, Kenta
Sekiguchi, Yuichiro
Shibata, Masaru
contents We examine nucleosynthesis in the ejecta of black hole-neutron star mergers based on the results of long-term neutrino-radiation-magnetohydrodynamics simulations for the first time. We find that the combination of dynamical and post-merger ejecta reproduces a solar-like r-process pattern. Moreover, the enhancement level of actinides is highly sensitive to the distribution of both electron fraction and the velocity of the dynamical ejecta. Our result implies that the mean electron fraction of dynamical ejecta should be >~ 0.05 in order to reconcile the nucleosynthetic abundances with those in r-process-enhanced, actinide-boost stars. Since the tidal ejecta preserve the neutron-richness in the inner crust of pre-merging neutron stars, this result provides an important constraint for nuclear equations of state, if black hole-neutron star mergers are responsible for actinide-boost stars.
format Preprint
id arxiv_https___arxiv_org_abs_2212_04507
institution arXiv
publishDate 2022
record_format arxiv
spellingShingle Actinide-boosting r Process in Black Hole-Neutron Star Merger Ejecta
Wanajo, Shinya
Fujibayashi, Sho
Hayashi, Kota
Kiuchi, Kenta
Sekiguchi, Yuichiro
Shibata, Masaru
High Energy Astrophysical Phenomena
We examine nucleosynthesis in the ejecta of black hole-neutron star mergers based on the results of long-term neutrino-radiation-magnetohydrodynamics simulations for the first time. We find that the combination of dynamical and post-merger ejecta reproduces a solar-like r-process pattern. Moreover, the enhancement level of actinides is highly sensitive to the distribution of both electron fraction and the velocity of the dynamical ejecta. Our result implies that the mean electron fraction of dynamical ejecta should be >~ 0.05 in order to reconcile the nucleosynthetic abundances with those in r-process-enhanced, actinide-boost stars. Since the tidal ejecta preserve the neutron-richness in the inner crust of pre-merging neutron stars, this result provides an important constraint for nuclear equations of state, if black hole-neutron star mergers are responsible for actinide-boost stars.
title Actinide-boosting r Process in Black Hole-Neutron Star Merger Ejecta
topic High Energy Astrophysical Phenomena
url https://arxiv.org/abs/2212.04507