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Title: The effect of radial migration on galactic disks

Abstract

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, ifmore » 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.« less

Authors:
;  [1];  [2];  [3]
  1. Department of Astronomy, University of Wisconsin, 2535 Sterling Hall, 475 North Charter Street, Madison, WI 53076 (United States)
  2. Department of Physics and Astronomy, University of Victoria, Victoria, BC, V8P 5C2 (Canada)
  3. Observatorio Astronómico, Universidad Nacional de Córdoba, Córdoba X5000BGR (Argentina)
Publication Date:
OSTI Identifier:
22370375
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 794; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; AMPLITUDES; ANGULAR MOMENTUM; AXIAL SYMMETRY; DISPERSIONS; DISTURBANCES; EXCURSIONS; GALAXIES; MIGRATION; NONLUMINOUS MATTER; ORBITS; PERTURBATION THEORY; SPATIAL DISTRIBUTION; STAR EVOLUTION; STARS; VELOCITY

Citation Formats

Vera-Ciro, Carlos, D'Onghia, Elena, Navarro, Julio, and Abadi, Mario, E-mail: ciro@astro.wisc.edu. The effect of radial migration on galactic disks. United States: N. p., 2014. Web. doi:10.1088/0004-637X/794/2/173.
Vera-Ciro, Carlos, D'Onghia, Elena, Navarro, Julio, & Abadi, Mario, E-mail: ciro@astro.wisc.edu. The effect of radial migration on galactic disks. United States. doi:10.1088/0004-637X/794/2/173.
Vera-Ciro, Carlos, D'Onghia, Elena, Navarro, Julio, and Abadi, Mario, E-mail: ciro@astro.wisc.edu. 2014. "The effect of radial migration on galactic disks". United States. doi:10.1088/0004-637X/794/2/173.
@article{osti_22370375,
title = {The effect of radial migration on galactic disks},
author = {Vera-Ciro, Carlos and D'Onghia, Elena and Navarro, Julio and Abadi, Mario, E-mail: ciro@astro.wisc.edu},
abstractNote = {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.},
doi = {10.1088/0004-637X/794/2/173},
journal = {Astrophysical Journal},
number = 2,
volume = 794,
place = {United States},
year = 2014,
month =
}
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