THE EFFECT OF RADIAL MIGRATION ON GALACTIC DISKS

By C. Vera-Ciro, E. D’Onghia, J. Navarro, M. Abadi. 2014

91 citations recorded by the source corpus.

We study the radial migration of stars driven by recurring multi-arm spiral features in an exponential disk embedded in a dark matter halo. The spiral perturbations redistribute angular momentum within the disk and lead to substantial radial displacements of individual stars, in a manner that largely preserves the circularity of their orbits and that results, after 5 Gyr (∼40 full rotations at the disk scale length), in little radial heating and no appreciable changes to the vertical or radial structure of the disk. Our results clarify a number of issues related to the spatial distribution and kinematics of migrators. In particular, we find that migrators are a heavily biased subset of stars with preferentially low vertical velocity dispersions. This “provenance bias” for migrators is not surprising in hindsight, for stars with small vertical excursions spend more time near the disk plane, and thus respond more readily to non-axisymmetric perturbations. We also find that the vertical velocity dispersion of outward migrators always decreases, whereas the opposite holds for inward migrators. To first order, newly arrived migrators simply replace stars that have migrated off to other radii, thus inheriting the vertical bias of the latter. Extreme migrators might therefore be recognized, if present, by the unexpectedly small amplitude of their vertical excursions. Our results show that migration, understood as changes in angular momentum that preserve circularity, can strongly affect the thin disk, but cast doubts on models that envision the Galactic thick disk as a relic of radial migration.

Subfields: Astronomy and Astrophysics, Instrumentation

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Citations in the corpus

Yule-Simpson’s paradox in Galactic Archaeology (2019, background): “This finding supports work showing that migration does not contribute to thick disk formation (e.g., Minchev et al. 2012, 2014a; Vera-Ciro et al. 2014; Grand et al. 2016, see also discussion in §1), except in redistributing stars heated by external mechanisms (Quinn et al. 1993; Villalobos & Helmi…”
The Lives of Stars: Insights from the TGAS–RAVE–LAMOST Data Set (2018, methodology): “Further, Vera-Ciro et al. (2014), using a disk with spiral arms embedded in a dark matter halo, showed that churning was most efficient on stars with low vertical velocity dispersions.”
A-type stars in the Canada–France Imaging Survey – II. Tracing the height of the disc at large distances with Blue Stragglers (2018, background): “However, Vera-Ciro et al. (2014) and Vera-Ciro, D’Onghia & Navarro (2016) argued that the inward migrators instead induce a thinning of the disc rather than the outward migrators causing a thickening.”
Chemodynamical evolution of the Milky Way disk II: Variations with Galactic radius and height above the disk plane (2014, background): “Additionally, studying the high-resolution isolated disk simulation of D’Onghia et al. (2013), the recent work by Vera-Ciro et al. (2014) also found minimal eff ct of migration on the disk thickening.”
The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location (2018, result): “Consistent with that picture, most migration models (Roškar et al. 2012; Vera-Ciro et al. 2014; Daniel & Wyse 2018; Minchev et al. 2018) find that stars on circular orbits and close to the plane are those that move most easily, and this is what we see (cf. Solway et al. 2012).”
TRACING CHEMICAL EVOLUTION OVER THE EXTENT OF THE MILKY WAY'S DISK WITH APOGEE RED CLUMP STARS (2014, background): “…that this mechanism is able to produce a thick-disk component in agreement with many local observations, although more realistic simulations cast serious doubt on whether radial migration can produce enough (Roškar et al. 2013) or even any (Minchev et al. 2012b; Vera-Ciro et al. 2014b) heating.”
THE STELLAR POPULATION STRUCTURE OF THE GALACTIC DISK (2015, background): “…that may have occurred in the MW, current simulations do indicate that kinematic biases in the population of migrators are significant enough that little or no effect on the vertical structure of the disk should be expected (Minchev et al. 2012; Roškar et al. 2013; Vera-Ciro et al. 2014).”
Impacts of a flaring star-forming disc and stellar radial mixing on the vertical metallicity gradient (2016, methodology): “Vera-Ciro et al. (2014) discussed that the particles which migrate outward were preferentially vertically colder (their mean vertical height < |z| > and vertical velocity dispersion, σz, is lower) population, which they call ”provenance bias”.”
CHEMICAL CARTOGRAPHY WITH APOGEE: METALLICITY DISTRIBUTION FUNCTIONS AND THE CHEMICAL STRUCTURE OF THE MILKY WAY DISK (2015, methodology): “…of numerical simulations has found that migration can be accurately described as a Gaussian diffusion (e.g., Brunetti et al. 2011; Kubryk et al. 2014; Vera-Ciro et al. 2014); we use the simple analytic form above to approximate the effect of churning seen in these more realistic simulations.”
Constraints on Radial Migration in Spiral Galaxies - II. Angular momentum distribution and preferential migration (2018, background): “Studies of simulated disc galaxies support the notion that the vertical velocity dispersion of a population negatively affects the degree to which it migrates radially (Vera-Ciro et al. 2014, 2016; Grand et al. 2016).”
Constraining the Milky Way assembly history with Galactic Archaeology (2016, background): “Several independent groups, using different simulation techniques and setups, have confirmed that migration does not thicken the disc (Aumer et al. 2016; Grand et al. 2016; Martig et al. 2014b; Vera-Ciro et al. 2014).”
THE RELATIONSHIP BETWEEN MONO-ABUNDANCE AND MONO-AGE STELLAR POPULATIONS IN THE MILKY WAY DISK (2016, background): “Several independent groups have now supported these findings in more recent works (Martig et al. 2014; Vera-Ciro et al. 2014; Grand et al. 2016; Aumer et al. 2016), establishing this as a generic result of disk dynamics.”
The structure and dynamical evolution of the stellar disc of a simulated Milky Way-mass galaxy (2016, background): “Recent numerical calculations suggest, however, that radial migration has little impact on the disk thickening (e.g. Minchev et al. 2012; Vera-Ciro et al. 2014).”
Vertical disc heating in Milky Way-sized galaxies in a cosmological context (2015, background): “This confirms, for the first time, that the recent findings of isolated disc simulations (e.g., Minchev et al. 2012; Grand et al. 2012a; Vera-Ciro et al. 2014) hold in a cosmological context.”
Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient (2018, result): “This inversion was explained by Minchev et al. (2014a) (hereafter, MCM14, see also Rahimi et al. 2014; Miranda et al. 2016; Ma et al. 2017) as the effect of inside-out disk formation and disk flaring of monoage populations (their Fig.”