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arXiv · 1809.10991

Galactic Simulations of r-process Elemental Abundances

Christopher Haynes·Chiaki Kobayashi
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Abstract

We present the distributions of elemental abundance ratios using chemodynamical simulations which include four different neutron capture processes: magneto-rotational supernovae, neutron star mergers, neutrino driven winds, and electron capture supernovae. We examine both simple isolated dwarf disc galaxies and cosmological zoom-in simulations of Milky Way-type galaxies, and compare the [Eu/Fe] and [Eu/α] evolution with recent observations, including the HERMES-GALAH survey. We find that neither electron-capture supernovae or neutrino-driven winds are able to adequately produce heavy neutron-capture elements such as Eu in quantities to match observations. Both neutron-star mergers and magneto-rotational supernovae are able to produce these elements in sufficient quantities. Additionally, we find that the scatter in [Eu/Fe] and [Eu/α] at low metallicity ([Fe/H] < -1) and the [Eu/(Fe, α)] against [Fe/H] gradient of the data at high metallicity ([Fe/H] > -1) are both potential indicators of the dominant r-process site. Using the distribution in [Eu/(Fe, α] - [Fe/H] we predict that neutron star mergers alone are unable to explain the observed Eu abundances, but may be able to together with magneto-rotational supernovae.

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Christopher Haynes, Chiaki Kobayashi. 2018-12-18. Galactic Simulations of r-process Elemental Abundances. https://doi.org/10.1093/mnras%2Fsty3389

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