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Thermal-instability-driven Turbulent Mixing in Galactic Disks. I. Effective Mixing of Metals

Yang, Chao-Chin LU and Krumholz, Mark (2012) In The Astrophysical Journal 758(1).
Abstract
Observations show that radial metallicity gradients in disk galaxies are relatively shallow, if not flat, especially at large galactocentric distances and for galaxies in the high-redshift universe. Given that star formation and metal production are centrally concentrated, this requires a mechanism to redistribute metals. However, the nature of this mechanism is poorly understood, let alone quantified. To address this problem, we conduct magnetohydrodynamical simulations of a local shearing sheet of a thin, thermally unstable, gaseous disk driven by a background stellar spiral potential, including metals modeled as passive scalar fields. Contrary to what a simple α prescription for the gas disk would suggest, we find that turbulence driven... (More)
Observations show that radial metallicity gradients in disk galaxies are relatively shallow, if not flat, especially at large galactocentric distances and for galaxies in the high-redshift universe. Given that star formation and metal production are centrally concentrated, this requires a mechanism to redistribute metals. However, the nature of this mechanism is poorly understood, let alone quantified. To address this problem, we conduct magnetohydrodynamical simulations of a local shearing sheet of a thin, thermally unstable, gaseous disk driven by a background stellar spiral potential, including metals modeled as passive scalar fields. Contrary to what a simple α prescription for the gas disk would suggest, we find that turbulence driven by thermal instability is very efficient at mixing metals, regardless of the presence or absence of stellar spiral potentials or magnetic fields. The timescale for homogenizing randomly distributed metals is comparable to or less than the local orbital time in the disk. This implies that turbulent mixing of metals is a significant process in the history of chemical evolution of disk galaxies. (Less)
Please use this url to cite or link to this publication:
author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
galaxies: abundances galaxies: ISM galaxies: kinematics and dynamics instabilities methods: numerical turbulence
in
The Astrophysical Journal
volume
758
issue
1
publisher
University of Chicago Press
external identifiers
  • Scopus:84866897492
DOI
10.1088/0004-637X/758/1/48
language
English
LU publication?
no
id
26974101-f7e6-49cc-87f0-f1211e42a536 (old id 4361506)
date added to LUP
2014-03-20 16:50:28
date last changed
2016-11-27 04:32:32
@misc{26974101-f7e6-49cc-87f0-f1211e42a536,
  abstract     = {Observations show that radial metallicity gradients in disk galaxies are relatively shallow, if not flat, especially at large galactocentric distances and for galaxies in the high-redshift universe. Given that star formation and metal production are centrally concentrated, this requires a mechanism to redistribute metals. However, the nature of this mechanism is poorly understood, let alone quantified. To address this problem, we conduct magnetohydrodynamical simulations of a local shearing sheet of a thin, thermally unstable, gaseous disk driven by a background stellar spiral potential, including metals modeled as passive scalar fields. Contrary to what a simple α prescription for the gas disk would suggest, we find that turbulence driven by thermal instability is very efficient at mixing metals, regardless of the presence or absence of stellar spiral potentials or magnetic fields. The timescale for homogenizing randomly distributed metals is comparable to or less than the local orbital time in the disk. This implies that turbulent mixing of metals is a significant process in the history of chemical evolution of disk galaxies.},
  author       = {Yang, Chao-Chin and Krumholz, Mark},
  keyword      = {galaxies: abundances galaxies: ISM galaxies: kinematics and dynamics instabilities methods: numerical turbulence},
  language     = {eng},
  number       = {1},
  publisher    = {ARRAY(0xa564ad8)},
  series       = {The Astrophysical Journal},
  title        = {Thermal-instability-driven Turbulent Mixing in Galactic Disks. I. Effective Mixing of Metals},
  url          = {http://dx.doi.org/10.1088/0004-637X/758/1/48},
  volume       = {758},
  year         = {2012},
}