http://arxiv.org/abs/2204.11413
We present a multi-zone galactic chemical evolution model for the Milky Way that takes into account the updated yields of major nucleosynthesis channels. It incorporates physical processes like radial flow of gas in the disk and infall of fresh gas, along with stellar scattering processes like radial migration. For the first time using a physically motivated model, we qualitatively reproduce the observed $([{\rm Fe/H}], [\alpha/{\rm Fe}])$ distribution of stars at different Galactic locations, along with the age-$[\alpha/{\rm Fe}]$ and age-${\rm [Fe/H]}$ relations. The model successfully reproduces the bifurcated high- and low-$[\alpha/{\rm Fe}]$ sequences and sheds light on the origin of the thick disc. We analyse the effect of physical processes individually on the observed properties of the Galaxy. We show that radial flow of gas plays an important role in establishing the radial gradient for both ${\rm [Fe/H]}$ and $[\alpha/{\rm Fe}]$. The dichotomy in $[\alpha/{\rm Fe}]$ is primarily due to the sharp fall of $[\alpha/{\rm Fe}]$ with time and influenced by star formation history. We identify at least three independent factors that govern the rate of \alphafe{} declining with time: the fraction of white dwarfs that form SNe Ia, the timescale associated with the delay time distribution of Type Ia supernovae (SNe Ia), and star formation efficiency. ${\rm [Fe/H]}$ and $[\alpha/{\rm Fe}]$ evolve rapidly at early times but change gradually for at least the last 6 Gyr as they approach equilibrium values. The final equilibrium value of $[\alpha/{\rm Fe}]$ is governed by the ratio of SNe Ia to core-collapse supernovae (CCSN).
B. Chen, M. Hayden, S. Sharma, et. al.
Tue, 26 Apr 22
66/74
Comments: 21 pages, 12 figures, submitted
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