Lessons from the Auriga discs

• Verfasst von: Gómez, Facundo A. [VerfasserIn]
• Verfasst von: Grand, Robert J. J. [VerfasserIn]
• Verfasst von: Bustamente, Sebastian [VerfasserIn]
• Verfasst von: Pakmor, Rüdiger [VerfasserIn]
• Verfasst von: Springel, Volker [VerfasserIn]
• Titel: Lessons from the Auriga discs
• Titelzusatz: the hunt for the Milky Way's ex-situ disc is not yet over
• Verf.angabe: Facundo A. Gómez, Robert J.J. Grand, Antonela Monachesi, Simon D.M. White, Sebastian Bustamante, Federico Marinacci, Rüdiger Pakmor, Christine M. Simpson, Volker Springel, and Carlos S. Frenk
• E-Jahr: 2017
• Jahr: 26 Apr 2017
• Umfang: 13 S.
• Fussnoten: Gesehen am 11.11.2023
• Titel Quelle: Enthalten in: De.arxiv.org
• Ort Quelle: [S.l.] : Arxiv.org, 1991
• Jahr Quelle: 2017
• Band/Heft Quelle: (2017) Artikel-Nummer 1704.08261, 13 Seiten
• DOI: doi:10.48550/arXiv.1704.08261
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: Astrophysics - Astrophysics of Galaxies
• K10plus-PPN: 1571378073

Abstract

We characterize the contribution from accreted material to the galactic discs of the Auriga Project, a set of high resolution magnetohydrodynamic cosmological simulations of late-type galaxies performed with the moving-mesh code AREPO. Our goal is to explore whether a significant accreted (or ex-situ) stellar component in the Milky Way disc could be hidden within the near-circular orbit population, which is strongly dominated by stars born in-situ. One third of our models shows a significant ex-situ disc but this fraction would be larger if constraints on orbital circularity were relaxed. Most of the ex-situ material ($\gtrsim 50\%$) comes from single massive satellites ($> 6 \times 10^{10}~M_{\odot}$). These satellites are accreted with a wide range of infall times and inclination angles (up to $85^{\circ}$). Ex-situ discs are thicker, older and more metal-poor than their in-situ counterparts. They show a flat median age profile, which differs from the negative gradient observed in the in-situ component. As a result, the likelihood of identifying an ex-situ disc in samples of old stars on near-circular orbits increases towards the outskirts of the disc. We show three examples that, in addition to ex-situ discs, have a strongly rotating dark matter component. Interestingly, two of these ex-situ stellar discs show an orbital circularity distribution that is consistent with that of the in-situ disc. Thus, they would not be detected in typical kinematic studies.