http://arxiv.org/abs/1809.10991
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/{\alpha}] 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/{\alpha}] at low metallicity ([Fe/H] < -1) and the [Eu/(Fe, {\alpha})] 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, {\alpha}] – [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.
C. Haynes and C. Kobayashi
Mon, 1 Oct 18
33/46
Comments: N/A
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