Published November 2017
| Version v1
Journal article
What the Milky Way bulge reveals about the initial metallicity gradients in the disc
Contributors
Others:
- Galaxies, Etoiles, Physique, Instrumentation (GEPI) ; Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
- Joseph Louis LAGRANGE (LAGRANGE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; Université Côte d'Azur (UniCA)-Université Côte d'Azur (UniCA)-Centre National de la Recherche Scientifique (CNRS)
- Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA) ; École normale supérieure - Paris (ENS-PSL) ; Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris Sciences et Lettres (PSL)-Université de Cergy Pontoise (UCP) ; Université Paris-Seine-Université Paris-Seine-Centre National de la Recherche Scientifique (CNRS)
- Collège de France - Chaire Galaxies et cosmologie ; Collège de France (CdF (institution))
- ANR-15-CE31-0007,MOD4Gaia,Modélisation de la Voie Lactée à l'epoque de Gaia(2015)
Description
We use APOGEE DR13 data to examine the metallicity trends in the Milky Way (MW) bulge and we explore their origin by comparing two N-body models of isolated galaxies that develop a bar and a boxy/peanut (b/p) bulge. Both models have been proposed as scenarios for reconciling a disc origin of the MW bulge with a negative vertical metallicity gradient. The first model is a superposition of co-spatial, i.e. overlapping, disc populations with different scale heights, kinematics, and metallicities. In this model the thick, metal-poor, and centrally concentrated disc populations contribute significantly to the stellar mass budget in the inner galaxy. The second model is a single disc with an initial steep radial metallicity gradient; this disc is mapped by the bar into the b/p bulge in such a way that the vertical metallicity gradient of the MW bulge is reproduced, as has been shown already in previous works in the literature. However, as we show here, the latter model does not reproduce the positive longitudinal metallicity gradient of the inner disc, nor the metal-poor innermost regions seen in the data. On the other hand, the model with co-spatial thin and thick disc populations reproduces all the aforementioned trends. We therefore see that it is possible to reconcile a (primarily) disc origin for the MW bulge with the observed trends in metallicity by mapping the inner thin and thick discs of the MW into a b/p. For this scenario to reproduce the observations, the α-enhanced, metal-poor, thick disc populations must have a significant mass contribution in the inner regions, as has been suggested for the Milky Way.
Abstract
International audienceAdditional details
Identifiers
- URL
- https://hal.science/hal-02190148
- URN
- urn:oai:HAL:hal-02190148v1
Origin repository
- Origin repository
- UNICA