Abstract
We analyse the structure and chemical enrichment of a Milky Way-like galaxy with a stellar mass of 2 × 1010M⊙, formed in a cosmological hydrodynamical simulation. It is disc dominated with a flat rotation curve, and has a disc scalelength similar to the Milky Way's, but a velocity dispersion that is ~50 per cent higher. Examining stars in narrow [Fe/H] and [α/Fe] abundance ranges, we find remarkable qualitative agreement between this simulation and observations. (a) The old stars lie in a thickened distribution with a short scalelength, while the young stars form a thinner disc, with scalelengths decreasing, as [Fe/H] increases. (b) Consequently, there is a distinct outward metallicity gradient. (c) Mono-abundance populations exist with a continuous distribution of scaleheights (from thin to thick). However, the simulated galaxy has a distinct and substantive very thick disc (hz ~ 1.5 kpc), not seen in the Milky Way. The broad agreement between simulations and observations allows us to test the validity of observational proxies used in the literature: we find in the simulation that mono-abundance populations are good proxies for single age populations (<1Gyr) for most abundances.
Original language | English (US) |
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Pages (from-to) | 625-634 |
Number of pages | 10 |
Journal | Monthly Notices of the Royal Astronomical Society |
Volume | 436 |
Issue number | 1 |
DOIs | |
State | Published - Nov 2013 |
Keywords
- Galaxies: formation
- Galaxies: structure
- Hydrodynamics
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science