Constraints on Radial Migration in Spiral Galaxies - II. Angular momentum distribution and preferential migration

By Kathryne J. Daniel, R. Wyse. 2018

26 citations recorded by the source corpus.

The orbital angular momentum of individual stars in galactic discs can be permanently changed through torques from transient spiral patterns. Interactions at the corotation resonance dominate these changes and have the further property of conserving orbital circularity. We derived in an earlier paper an analytic criterion that an unperturbed stellar orbit must satisfy in order for such an interaction to occur i.e. for it to be in a trapped orbit around corotation. We here use this criterion in an investigation of how the efficiency of induced radial migration for a population of disc stars varies with the angular momentum distribution of that population. We frame our results in terms of the velocity dispersion of the population, this being an easier observable than is the angular momentum distribution. Specifically, we investigate how the fraction of stars in trapped orbits at corotation varies with the velocity dispersion of the population, for a system with an assumed flat rotation curve. Our analytic results agree with the finding from simulations that radial migration is less effective in populations with 'hotter' kinematics. We further quantify the dependence of this trapped fraction on the strength of the spiral pattern, finding a higher trapped fraction for higher amplitude perturbations.

Subfields: Astronomy and Astrophysics

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Citations in the corpus

Yule-Simpson’s paradox in Galactic Archaeology (2019, background): “Indeed, larger changes in guiding radii (or angular momentum) are expected for the coldest subpopulations in a given age group (e.g., Vera-Ciro et al. 2014; Daniel & Wyse 2018).”
The GALAH survey and Gaia DR2: dissecting the stellar disc’s phase space by age, action, chemistry, and location (2018, background): “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).”
Estimating stellar birth radii and the time evolution of Milky Way’s ISM metallicity gradient (2018, background): “Since older samples have experienced more migration, their gradients are expected to have flattened more, although it should be kept in mind that older stars are also kinematically hot and, thus, not so prone to migration (Minchev et al. 2012a; Daniel & Wyse 2018).”