Galactic Isotopic Decomposition for the Sculptor Dwarf Spheroidal Galaxy. (arXiv:2102.02790v2 [astro-ph.GA] UPDATED)

Galactic Isotopic Decomposition for the Sculptor Dwarf Spheroidal Galaxy. (arXiv:2102.02790v2 [astro-ph.GA] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Pandey_K/0/1/0/all/0/1">Kanishk Pandey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+West_C/0/1/0/all/0/1">Christopher West</a>

Stellar evolution models require initial isotopic abundance sets as input,
but these abundances are incomplete outside the solar neighborhood, are
challenging to infer from elemental observations, and are galaxy specific.
Compositions different from the Milky Way (MW) have distinct chemical histories
and are important to explore. We present an isotopic history model for the
Sculptor dwarf spheroidal galaxy (dSph) based on astrophysical processes, using
a complementary approach to GCE models, which can estimate isotopic abundances
for future nucleosynthesis studies. We approximated the isotopic composition of
Sculptor’s late stage evolution using the OMEGA chemical evolution code and
used Big Bang Nucleosynthesis (BBN) predictions as the other boundary
condition. Isotopic abundances were scaled from late stage evolution to BBN
values according to the astrophysical processes responsible for their
production. The isotopic abundances were summed into elemental abundances and
fit to observational Sculptor abundance data to tune the free parameters. The
completed model gives the average isotopic history of Sculptor for massive
star, Type Ia SNe, main $s$-process peak, and $r$-process contributions. We
find that Type Ia SNe contribute $approx$ 86 per cent to the late stage
evolution Fe abundance, which agrees with other dSph chemical evolution
studies, and is greater than typical MW values of $approx$ 70 per cent found
using a similar process. The model also finds that neutron star mergers
contribute $approx$ 30 per cent to the late stage evolution Eu abundance,
suggesting that CCSNe may be the dominant $r$-process progenitors in dSphs.

Stellar evolution models require initial isotopic abundance sets as input,
but these abundances are incomplete outside the solar neighborhood, are
challenging to infer from elemental observations, and are galaxy specific.
Compositions different from the Milky Way (MW) have distinct chemical histories
and are important to explore. We present an isotopic history model for the
Sculptor dwarf spheroidal galaxy (dSph) based on astrophysical processes, using
a complementary approach to GCE models, which can estimate isotopic abundances
for future nucleosynthesis studies. We approximated the isotopic composition of
Sculptor’s late stage evolution using the OMEGA chemical evolution code and
used Big Bang Nucleosynthesis (BBN) predictions as the other boundary
condition. Isotopic abundances were scaled from late stage evolution to BBN
values according to the astrophysical processes responsible for their
production. The isotopic abundances were summed into elemental abundances and
fit to observational Sculptor abundance data to tune the free parameters. The
completed model gives the average isotopic history of Sculptor for massive
star, Type Ia SNe, main $s$-process peak, and $r$-process contributions. We
find that Type Ia SNe contribute $approx$ 86 per cent to the late stage
evolution Fe abundance, which agrees with other dSph chemical evolution
studies, and is greater than typical MW values of $approx$ 70 per cent found
using a similar process. The model also finds that neutron star mergers
contribute $approx$ 30 per cent to the late stage evolution Eu abundance,
suggesting that CCSNe may be the dominant $r$-process progenitors in dSphs.

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