The origin of stellar populations in the Galactic bulge from chemical abundances

Research output: Contribution to journalArticle

Abstract

In this work, we study the formation and chemical evolution of the Galactic bulge with particular focus on the abundance pattern ([Mg/Fe] versus [Fe/H]), metallicity, and age distribution functions. We consider detailed chemical evolution models for the Galactic bulge and inner disc, with the aim of shedding light on the connection between these components and the origin of bulge stars. In particular, we first present a model assuming a fast and intense star formation, with the majority of bulge stars forming on a time-scale less than 1 Gyr. Then we analyse the possibility of two distinct stellar populations in the bulge, as suggested by Gaia-ESO and APOGEE data. These two populations, one metal poor and the other metal rich, can have had two different origins: (i) the metal rich formed after a stop of -250 Myr in the star formation rate of the bulge or (ii) the metal-rich population is made of stars formed in the inner disc and brought into the bulge by the early secular evolution of the bar. We also examine the case of multiple starbursts in the bulge with consequent formation of multiple populations, as suggested by studies of microlensed stars. After comparing model results and observations, we suggest that the most likely scenario is that there are two main stellar populations, both made mainly by old stars (>10 Gyr), with the metal-rich and younger one formed from inner thin disc stars, in agreement with kinematical arguments. However, on the basis of dynamical simulations, we cannot completely exclude that the second population formed after a stop in the star formation during the bulge evolution, so that all the stars formed in situ.

Details

Authors
  • F. Matteucci
  • V. Grisoni
  • E. Spitoni
  • A. Zulianello
  • A. Rojas-Arriagada
  • M. Schultheis
  • N. Ryde
Organisations
External organisations
  • University of Trieste
  • INAF Astronomical Observatory of Trieste
  • INFN Section of Trieste
  • Aarhus University
  • Pontifical Catholic University of Chile
  • Millennium Institute of Astrophysics
  • Côte d'Azur Observatory
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Astronomy, Astrophysics and Cosmology

Keywords

  • galaxies: abundances, galaxies: evolution, galaxies: ISM
Original languageEnglish
Article numberstz1647
Pages (from-to)5363-5371
Number of pages9
JournalMonthly Notices of the Royal Astronomical Society
Volume487
Issue number4
Publication statusPublished - 2019 Jun 25
Publication categoryResearch
Peer-reviewedYes