We employ our Bayesian Machine Learning framework BINGO (Bayesian INference for Galactic archaeOlogy) to obtain high-quality stellar age estimates for 68 360 red giant and red clump stars present in the 17th data release of the Sloan Digital Sky Survey, the APOGEE-2 high-resolution spectroscopic survey. By examining the denoised age-metallicity relationship of the Galactic disc stars, we identify a drop in metallicity with an increase in [Mg/Fe] at an early epoch, followed by a chemical enrichment episode with increasing [Fe/H] and decreasing [Mg/Fe]. This result is congruent with the chemical evolution induced by an early-epoch gas-rich merger identified in the Milky Way-like zoom-in cosmological simulation Auriga. In the initial phase of the merger of Auriga 18 there is a drop in metallicity due to the merger diluting the metal content and an increase in the [Mg/Fe] of the primary galaxy. Our findings suggest that the last massive merger of our Galaxy, the Gaia-Sausage-Enceladus, was likely a significant gas-rich merger and induced a starburst, contributing to the chemical enrichment and building of the metal-rich part of the thick disc at an early epoch.

Chasing the impact of the Gaia-Sausage-Enceladus merger on the formation of the Milky Way thick disc / Ciuca I.; Kawata D.; Ting Y.-S.; Grand R.J.J.; Miglio A.; Hayden M.; Baba J.; Fragkoudi F.; Monty S.; Buder S.; Freeman K.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. LETTERS. - ISSN 1745-3933. - ELETTRONICO. - 528:1(2024), pp. L122-L126. [10.1093/mnrasl/slad033]

Chasing the impact of the Gaia-Sausage-Enceladus merger on the formation of the Milky Way thick disc

Miglio A.;
2024

Abstract

We employ our Bayesian Machine Learning framework BINGO (Bayesian INference for Galactic archaeOlogy) to obtain high-quality stellar age estimates for 68 360 red giant and red clump stars present in the 17th data release of the Sloan Digital Sky Survey, the APOGEE-2 high-resolution spectroscopic survey. By examining the denoised age-metallicity relationship of the Galactic disc stars, we identify a drop in metallicity with an increase in [Mg/Fe] at an early epoch, followed by a chemical enrichment episode with increasing [Fe/H] and decreasing [Mg/Fe]. This result is congruent with the chemical evolution induced by an early-epoch gas-rich merger identified in the Milky Way-like zoom-in cosmological simulation Auriga. In the initial phase of the merger of Auriga 18 there is a drop in metallicity due to the merger diluting the metal content and an increase in the [Mg/Fe] of the primary galaxy. Our findings suggest that the last massive merger of our Galaxy, the Gaia-Sausage-Enceladus, was likely a significant gas-rich merger and induced a starburst, contributing to the chemical enrichment and building of the metal-rich part of the thick disc at an early epoch.
2024
Chasing the impact of the Gaia-Sausage-Enceladus merger on the formation of the Milky Way thick disc / Ciuca I.; Kawata D.; Ting Y.-S.; Grand R.J.J.; Miglio A.; Hayden M.; Baba J.; Fragkoudi F.; Monty S.; Buder S.; Freeman K.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. LETTERS. - ISSN 1745-3933. - ELETTRONICO. - 528:1(2024), pp. L122-L126. [10.1093/mnrasl/slad033]
Ciuca I.; Kawata D.; Ting Y.-S.; Grand R.J.J.; Miglio A.; Hayden M.; Baba J.; Fragkoudi F.; Monty S.; Buder S.; Freeman K.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/958290
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