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The Fall of a Giant. Chemical evolution of Enceladus, alias the Gaia Sausage

Vincenzo, Fiorenzo; Spitoni, Emanuele; Calura, Francesco; Matteucci, Francesca; Silva Aguirre, Victor; Miglio, Andrea; Cescutti, Gabriele

Authors

Fiorenzo Vincenzo

Emanuele Spitoni

Francesco Calura

Francesca Matteucci

Victor Silva Aguirre

Andrea Miglio

Gabriele Cescutti



Abstract

We present the first chemical evolution model for Enceladus, alias the Gaia Sausage, to investigate the star formation history of one of the most massive satellites accreted by the Milky Way during a major merger event. Our best chemical evolution model for Enceladus nicely fits the observed stellar [$\alpha$/Fe]-[Fe/H] chemical abundance trends, and reproduces the observed stellar metallicity distribution function, by assuming low star formation efficiency, fast infall time scale, and mild outflow intensity. We predict a median age for Enceladus stars $12.33^{+0.92}_{-1.36}$ Gyr, and - at the time of the merger with our Galaxy ($\approx10$ Gyr ago from Helmi et al.) - we predict for Enceladus a total stellar mass $M_{\star} \approx 5 \times 10^{9}\,\text{M}_{\odot}$. By looking at the predictions of our best model, we discuss that merger events between the Galaxy and systems like Enceladus may have inhibited the gas accretion onto the Galaxy disc at high redshifts, heating up the gas in the halo. This scenario could explain the extended period of quenching in the star formation activity of our Galaxy about 10 Gyr ago, which is predicted by Milky Way chemical evolution models, in order to reproduce the observed bimodality in [$\alpha$/Fe]-[Fe/H] between thick- and thin-disc stars.

Citation

Vincenzo, F., Spitoni, E., Calura, F., Matteucci, F., Silva Aguirre, V., Miglio, A., & Cescutti, G. (2019). The Fall of a Giant. Chemical evolution of Enceladus, alias the Gaia Sausage. Monthly Notices of the Royal Astronomical Society: Letters, 487(1), L47–L52. https://doi.org/10.1093/mnrasl/slz070

Journal Article Type Article
Acceptance Date May 7, 2019
Online Publication Date May 14, 2019
Publication Date 2019-07
Deposit Date Mar 12, 2022
Publicly Available Date Mar 28, 2022
Journal Monthly Notices of the Royal Astronomical Society: Letters
Print ISSN 1745-3933
Electronic ISSN 1745-3933
Publisher Oxford University Press
Peer Reviewed Peer Reviewed
Volume 487
Issue 1
Pages L47–L52
DOI https://doi.org/10.1093/mnrasl/slz070
Keywords Astrophysics of Galaxies
Public URL https://hull-repository.worktribe.com/output/3946259

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Copyright Statement
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society: Letters ©: 2019 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.





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