Journal article
The Milky Way’s bulge star formation history as constrained from its bimodal chemical abundance distribution
Monthly notices of the Royal Astronomical Society, Vol.497(3), pp.3557-3570
09/01/2020
DOI: 10.1093/mnras/staa2205
Abstract
ABSTRACT
We conduct a quantitative analysis of the star formation history (SFH) of the Milky Way’s (MW) bulge by exploiting the constraining power of its stellar [Fe/H] and [Mg/Fe] distribution functions. Using Apache Point Observatory Galactic Evolution Experiment survey data, we confirm the previously established bimodal [Mg/Fe]–[Fe/H] distribution within 3 kpc of the inner Galaxy. To fit the chemical bimodal distribution, we use a simple but flexible star formation framework, which assumes two distinct stages of gas accretion and star formation, and systematically evaluate a wide multidimensional parameter space. We find that the data favour a three-phase SFH that consists of an initial starburst, followed by a rapid star formation quenching episode, and a lengthy, quiescent secular evolution phase. The metal-poor, high-α bulge stars ([Fe/H] < 0.0 and [Mg/Fe] > 0.15) are formed rapidly (<2 Gyr) during the early starburst. The density gap between the high- and low-α sequences is due to the quenching process. The metal-rich, low-α population ([Fe/H] > 0.0 and [Mg/Fe] < 0.15) then accumulates gradually through inefficient star formation during the secular phase. This is qualitatively consistent with the early SFH of the inner disc. Given this scenario, a notable fraction of young stars (age <5 Gyr) is expected to persist in the bulge. Combined with extragalactic observations, these results suggest that a rapid star formation quenching process is responsible for bimodal distributions in both the MW’s stellar populations and in the general galaxy population and thus plays a critical role in galaxy evolution.
Details
- Title: Subtitle
- The Milky Way’s bulge star formation history as constrained from its bimodal chemical abundance distribution
- Creators
- Jianhui Lian - University of UtahGail Zasowski - University of UtahSten Hasselquist - University of UtahDavid M Nataf - Johns Hopkins UniversityDaniel Thomas - University of PortsmouthChristian Moni Bidin - Universidad Católica del NorteJosé G Fernández-Trincado - University of AtacamaD A Garcia-Hernandez - Instituto de Astrofísica de CanariasRichard R Lane - Pontificia Universidad Católica de ChileSteven R Majewski - University of VirginiaAlexandre Roman-Lopes - University of La SerenaMathias Schultheis - Observatoire de la Côte d’Azur
- Resource Type
- Journal article
- Publication Details
- Monthly notices of the Royal Astronomical Society, Vol.497(3), pp.3557-3570
- DOI
- 10.1093/mnras/staa2205
- ISSN
- 0035-8711
- eISSN
- 1365-2966
- Number of pages
- 14
- Language
- English
- Date published
- 09/01/2020
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984701722802771
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