20.500.12556/RUL-191284 The GALAH survey: neutron-capture elemental abundances for 350 000 Gaia-RVS spectra and the chemodynamics of accreted structures We present a comprehensive data-driven spectroscopic analysis of 357 415 red giant stars using Gaia DR3 Radial Velocity Spectrometer (RVS) spectra (8460-8700 Å; $R \approx 11500$), aimed at deriving homogenous stellar parameters and elemental abundances (collectively referred to as stellar labels). We employ The Cannon, a generative model based on 2747 giants in common with GALactic Archaeology with HERMES (GALAH) DR4, adopting GALAH labels (⁠$R \approx 28000$) for training. The resulting model predicts 11 stellar labels for RVS giants: effective temperature (⁠$T_{eff}$), surface gravity ($\mathrm{log} g$⁠), projected rotational velocity ($v \sin{i}$⁠), and abundances of [Fe/H], [Ca/Fe], [Si/Fe], [Ni/Fe], [Ti/Fe], as well as the neutron-capture elements [Zr/Fe], [Ce/Fe], and [Nd/Fe]. Building on these results, we develop a probabilistic framework to chemically identify debris from the Gaia-Sausage-Enceladus (GSE) accretion event. A logistic regression classifier, optimized via Markov chain Monte Carlo sampling and trained on a small reference sample of GSE members and comparison stars, identifies stars with high GSE membership probabilities based solely on their chemical abundances, with the resulting candidates exhibiting distinctive abundance-ratio patterns, including [Ca/Ti], [Ti/Ce], and [Nd/Zr]. Applying independent kinematic constraints yields a robust sample of GSE candidates, demonstrating that the characteristic chemical signatures remain consistent after applying these constraints. This work demonstrates the potential of data-driven analysis techniques to extract detailed chemical information from medium-resolution spectra and establishes a framework for tracing Galactic accretion events using chemical abundances. stars galaxies chemical abundances galaxy evolution spectroscopic analysis GALAH sky survey zvezde galaksije kemična sestava razvoj galaksij spektroskopski pregledi neba GALAH true false true Angleški jezik Slovenski jezik Članek v reviji 2026-11-13 13:53:22 2026-11-13 13:53:24 2026-11-14 04:31:06 0000-00-00 00:00:00 2026 0 0 24 str. iss. 4 Vol. 550 Aug. 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 524 1365-2966 10.1093/mnras/stag1142 305278467 https://academic.oup.com/mnras/article/550/4/stag1142/8709287 1 1947f07a-df61-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=253338 stag1142.pdf stag1142.pdf 1 9A20637E9D2FF41098704840FA9B2DAE 886cf1c7bbe80306b8b21c3ff4017ab8a9e7724647c2e7e7a46f0980f92c67dd 412e94aa-df65-11f1-aea2-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=253344 Fakulteta za matematiko in fiziko 0 0 0