THE GENESIS OF THE MILKY WAY'S THICK DISK VIA STELLAR MIGRATION

By Sarah Loebman, Rok Roskar, V. Debattista, Željko Ivezic´, Thomas R. Quinn, James Wadsley. 2010

185 citations recorded by the source corpus.

We compare the spatial, kinematic, and metallicity distributions of stars in the Milky Way disk, as observed by the Sloan Digital Sky Survey and Geneva–Copenhagen Survey, to predictions made by N-body simulations that naturally include radial migration as proposed by Sellwood & Binney. In these simulations, stars that migrate radially outward feel a decreased restoring force, consequentially they reach larger heights above the mid-plane. We find that this model is in qualitative agreement with observational data and can explain the disk's double-exponential vertical structure and other characteristics as due to internal evolution. In particular, the model reproduces observations of stars in the transition region between exponential components, which do not show a strong correlation between rotational velocity and metallicity. Although such a correlation is present in young stars because of epicyclic motions, radial migration efficiently mixes older stars and weakens the correlation. Classifying stars as members of the thin or thick disk by either velocity or metallicity leads to an apparent separation in the other property, as observed. We find a much stronger separation when using [α/Fe], which is a good proxy for stellar age. The model success is remarkable because the simulation was not tuned to reproduce the Galaxy, hinting that the thick disk may be a ubiquitous Galactic feature generated by stellar migration. Nonetheless, we cannot exclude the possibility that some fraction of the thick disk is a fossil of a more violent history, nor can radial migration explain thick disks in all galaxies, most strikingly those which counterrotate with respect to the thin disk.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/bf98964c1f24213d06cc4d30eaacb6ac468bea72

How researchers see this paper

The researchers whose trusted networks rank it highest, strongest advocate first. Every researcher gets a different order.

In Astronomy and Astrophysics

In Instrumentation

Citations in the corpus

Constraining the Milky Way assembly history with Galactic Archaeology (2016, background): “Several works (e.g., Loebman et al. 2011; Schönrich & Binney 2009b) have also proposed that radial migration can give rise to thick disc formation by bringing out high-velocity-dispersion stellar populations from the inner disc and the bulge.”
THE SPATIAL STRUCTURE OF MONO-ABUNDANCE SUB-POPULATIONS OF THE MILKY WAY DISK (2011, background): “Thick-disk components can also be formed internally through star formation following a gas-rich merger (e.g., Brook et al. 2004) or by quiescent internal dynamical evolution (Schönrich & Binney 2009a,b; Loebman et al. 2011).”
Vertical disc heating in Milky Way-sized galaxies in a cosmological context (2015, background): “Recent N-body work has also speculated at the generation of thick discs via radial migration (e.g., Loebman et al. 2011), and it has been demonstrated that star particles that move from the inner to outer disc increase their vertical distance from the mid-plane, owing to the lower surface gravity…”
The Milky Way’s stellar disk (2013, background): “…the disk could have been born with larger velocity dispersion than is typical at z ≈ 0 (Bournaud et al. 2009; Ceverino et al. 2012), or purely internal dynamical evolution due to radial migration may gradually thicken the disk (Schönrich & Binney 2009; Loebman et al. 2011; Minchev et al. 2012a).”
Chemodynamical evolution of the Milky Way disk - I. The solar vicinity (2012, background): “Similarly, the increase of disk thickness with time found inthe simulation by Roškar et al. (2008) has been attributed to migration in the works by Sales et al. (2009) and Loebman et al. (2011).”
THE STELLAR POPULATION STRUCTURE OF THE GALACTIC DISK (2015, background): “…Abadi et al. 2003; Brook et al. 2004) or through radial migration (e.g., Sellwood & Binney 2002; Schönrich & Binney 2009; Minchev & Famaey 2010; Loebman et al. 2011), the possibility that (at least some part of) the stellar disk formed “upside-down” with its current thickness has recently…”
OXYGEN ABUNDANCES IN NEARBY FGK STARS AND THE GALACTIC CHEMICAL EVOLUTION OF THE LOCAL DISK AND HALO (2013, methodology): “However, bottom-up models in which radial mixing is an important component of the process of Galactic disk formation have been shown to explain these data as successfully as the merger models, and in some cases even better (e.g., Schönrich & Binney 2009b; Loebman et al. 2011; Bird et al. 2012).”
New constraints on the chemical evolution of the solar neighbourhood and galactic disc(s) - improved astrophysical parameters for the Geneva-Copenhagen Survey (2011, background): “…a thick component with time, if this is caused by to internal (scattering, dynamical interaction or radial mixing, e.g., Schönrich & Binney 2009b; Loebman et al. 2010) or external (satellite accretion, mergers of gas-rich systems, minor mergers, e.g., Abadi et al. 2003; Brook et al. 2007;…”
CHEMICAL CARTOGRAPHY WITH APOGEE: METALLICITY DISTRIBUTION FUNCTIONS AND THE CHEMICAL STRUCTURE OF THE MILKY WAY DISK (2015, background): “…mixing of gas and stars from their original birth radii has also been proposed as an important process in the evolution of the Milky Way disk (e.g., Wielen et al. 1996; Sellwood & Binney 2002; Roškar et al. 2008; Schönrich & Binney 2009; Loebman et al. 2011; Solway et al. 2012; Halle et al. 2015).”
The structure and dynamical evolution of the stellar disc of a simulated Milky Way-mass galaxy (2016, background): “…al. 2010; Faure et al. 2014; Yurin & Springel 2015; Grand et al. 2016), (2) radial migration (e.g. Sellwood & Binney 2002; Schönrich & Binney 2009b; Loebman et al. 2011; however, see e.g. Minchev et al. 2012), (3) perturbation of satellites and sub-halos (e.g. Quinn et al. 1993; Kazantzidis et al.…”
Thin disc, thick disc and halo in a simulated galaxy (2012, methodology): “At these times, it thus resembles the models of Loebman et al. (2011), and it is interesting that their collapse model also initially forms a relatively short, kinematically hot, disc at high redshift before the thin-disc formation begins.”
The age–metallicity structure of the Milky Way disc using APOGEE (2017, methodology): “More recently, the effects of radial migration (e.g. Sellwood & Binney 2002) were added, in order to produce models that agree better with the observations (e.g. Loebman et al. 2011; Schönrich & Binney 2009a; Spitoni et al. 2015; Kubryk et al. 2015) .”
LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) — The survey's science plan (2012, background): “Loebman et al. (2011) pointed out that theα-abundance is a valuable indicator of age that can be used to help to confirm the radial migration.”