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arXiv · 1301.5318

MaGICC Thick Disk I: Comparing a Simulated Disk Formed with Stellar Feedback to the Milky Way

G. S. Stinson·J. Bovy·H. -W. Rix·C. Brook·R. Roškar·J. J. Dalcanton·A. V. Macciò·J. Wadsley·H. M. P. Couchman·T. R. Quinn
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Abstract

We analyse the structure and chemical enrichment of a Milky Way-like galaxy with a stellar mass of 2 10^{10} M_sun, formed in a cosmological hydrodynamical simulation. It is disk-dominated with a flat rotation curve, and has a disk scale length similar to the Milky Way's, but a velocity dispersion that is ~50% higher. Examining stars in narrow [Fe/H] and [\alpha/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 scale length, while the young stars form a thinner disk, with scale lengths decreasing, as [Fe/H] increases. b) Consequently, there is a distinct outward metallicity gradient. c) Mono-abundance populations exist with a continuous distribution of scale heights (from thin to thick). However, the simulated galaxy has a distinct and substantive very thick disk (h_z~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 (<1 Gyr) for most abundances.

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G. S. Stinson, J. Bovy, H. -W. Rix, C. Brook, R. Roškar, J. J. Dalcanton, A. V. Macciò, J. Wadsley, H. M. P. Couchman, T. R. Quinn. 2013-01-22. MaGICC Thick Disk I: Comparing a Simulated Disk Formed with Stellar Feedback to the Milky Way. https://doi.org/10.1093/mnras/stt1600

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