Galactic Genesis Decoded Abundances I: shared disk enrichment patterns

Abstract Elemental abundances in the Milky Way disk trace its star-formation and enrichment history, but predicting these abundances from theory is limited by uncertain nucleosynthetic yields and poorly constrained chemical evolution models. Large surveys provide many abundances that enable multi-dimensional insight. However, having so much data available complicates joint visualisation and physical interpretation. Here, we examine the element abundances of 70,057 red giant stars from the Galactic Genesis survey (Fe/H −1), using 16 elements (O, Mg, Al, Si, S, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Ce, Nd). To tackle the challenges of joint-interpretation of these elements, we build a generative data-driven model, expressing each star’s abundance vector as a linear combination of a few (4) latent nucleosynthetic patterns. These patterns are shared among the population but vary in fraction between stars. The model accurately generates the measured abundances, with χ2 3 (5) for ∼ 80 % (95 %) of stars. Model failures, where stars’ abundances are not generated by the latent basis reveal accreted material and the role of multiple channels of metal-poor disk enrichment. We associate the recovered patterns, which represent high-precision (σP ∼ 3%) nucleosynthetic channels, with specific enrichment sources; (early and late) core-collapse supernovae, supernovae Type Ia, and asymptotic giant branch stars. We subsequently explore how the dominance of enrichment channels varies across age, metallicity and spatial extent of the disk, and show that enrichment patterns tightly couple to orbital properties. Mean pattern fractions vary smoothly with enrichment, and change rapidly across the valley between the high- and low-α sequences. Our results provide a framework for improving our understanding of Galactic evolution in the Milky Way.