Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: $R$-process enhancements of Gaia-Enceladus in GALAH DR3   The dominant site of production of $r$-process elements remains unclear
despite recent observations of a neutron star merger. Observational constraints
on the properties of the sites can be obtained by comparing $r$-process
abundances in different environments. The recent Gaia data releases and large
samples from high-resolution optical spectroscopic surveys are enabling us to
compare $r$-process element abundances between stars formed in an accreted
dwarf galaxy, Gaia-Enceladus, and those formed in the Milky Way. We aim to
understand the origin of $r$-process elements in Gaia-Enceladus. We first
construct a sample of stars to study Eu abundances without being affected by
the detection limit. We then kinematically select 71 Gaia-Enceladus stars and
93 in-situ stars from the Galactic Archaeology with HERMES (GALAH) DR3, of
which 50 and 75 stars can be used to study Eu reliably. Gaia-Enceladus stars
clearly show higher ratios of [{Eu}/{Mg}] than in-situ stars. High [{Eu}/{Mg}]
along with low [{Mg}/{Fe}] are also seen in relatively massive satellite
galaxies such as the LMC, Fornax, and Sagittarius dwarfs. On the other hand,
unlike these galaxies, Gaia-Enceladus does not show enhanced [{Ba}/{Eu}] or
[{La}/{Eu}] ratios suggesting a lack of significant $s$-process contribution.
From comparisons with simple chemical evolution models, we show that the high
[{Eu}/{Mg}] of Gaia-Enceladus can naturally be explained by considering
$r$-process enrichment by neutron-star mergers with delay time distribution
that follows a similar power-law as type~Ia supernovae but with a shorter
minimum delay time.

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The categories of this paper are: chem-ph
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The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
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The categories of this paper are: plasm-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: hep-lat
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The categories of this paper are: cmp-lg
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: q-bio
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The categories of this paper are: adap-org
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The categories of this paper are: funct-an
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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The categories of this paper are: q-alg
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The categories of this paper are: supr-con