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The Structure and Dynamical Evolution of the Stellar Disk of a Simulated Milky Way-Mass Galaxy

Ma, Xiangcheng and Hopkins, Philip F. and Wetzel, Andrew R. and Kirby, Evan N. and Anglés-Alcázar, Daniel and Faucher-Giguère, Claude-André and Kereš, Dušan and Quataert, Eliot (2017) The Structure and Dynamical Evolution of the Stellar Disk of a Simulated Milky Way-Mass Galaxy. Monthly Notices of the Royal Astronomical Society, 467 (2). pp. 2430-2444. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20161107-114246249

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Abstract

We study the structure, age and metallicity gradients, and dynamical evolution using a cosmological zoom-in simulation of a Milky Way-mass galaxy from the Feedback in Realistic Environments project. In the simulation, stars older than 6 Gyr were formed in a chaotic, bursty mode and have the largest vertical scaleheights (1.5–2.5 kpc) by z = 0, while stars younger than 6 Gyr were formed in a relatively calm, stable disc. The vertical scaleheight increases with stellar age at all radii, because (1) stars that formed earlier were thicker ‘at birth’, and (2) stars were kinematically heated to an even thicker distribution after formation. Stars of the same age are thicker in the outer disc than in the inner disc (flaring). These lead to positive vertical age gradients and negative radial age gradients. The radial metallicity gradient is negative at the mid-plane, flattens at larger disc height |Z|, and turns positive above |Z| ∼ 1.5 kpc. The vertical metallicity gradient is negative at all radii, but is steeper at smaller radii. These trends broadly agree with observations in the Milky Way and can be naturally understood from the age gradients. The vertical stellar density profile can be well described by two components, with scaleheights 200–500 pc and 1–1.5 kpc, respectively. The thick component is a mix of stars older than 4 Gyr, which formed through a combination of several mechanisms. Our results also demonstrate that it is possible to form a thin disc in cosmological simulations even with a strong stellar feedback.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/stx273DOIArticle
https://academic.oup.com/mnras/article/2966031/ThePublisherArticle
https://arxiv.org/abs/1608.04133arXivDiscussion Paper
ORCID:
AuthorORCID
Hopkins, Philip F.0000-0003-3729-1684
Wetzel, Andrew R.0000-0003-0603-8942
Kirby, Evan N.0000-0001-6196-5162
Kereš, Dušan0000-0002-1666-7067
Quataert, Eliot0000-0001-9185-5044
Additional Information:© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 January 30. Received 2017 January 30; in original form 2016 August 14. Published: 01 February 2017. We thank David Nidever, Hans-Walter Rix, Charlie Conroy and Paul Torrey for useful discussions. We also acknowledge Oscar Agertz and Ivan Minchev for helpful comments after the first draft has appeared on arXiv, and the anonymous referee for a detailed report. The simulations used in this paper were run on XSEDE computational resources (allocations TG-AST120025, TG-AST130039 and TG-AST140023). The analysis was performed on the Caltech compute cluster ‘Zwicky’ (NSF MRI award #PHY-0960291). Support for PFH was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. ARW was supported by a Caltech-Carnegie Fellowship, in part through the Moore Center for Theoretical Cosmology and Physics at Caltech. DAA acknowledges support by a CIERA Postdoctoral Fellowship. C-AF-G was supported by NSF through grants AST-1412836 and AST-1517491, by NASA through grant NNX15AB22G, and by STScI through grants HST-AR-14293.001-A and HST-GO-14268.022-A. DK was supported by NSF grant AST-1412153 and funds from the University of California, San Diego. EQ was supported by NASA ATP grant 12-APT12-0183, by a Simons Investigator award from the Simons Foundation, and by the David and Lucile Packard Foundation.
Group:Moore Center for Theoretical Cosmology and Physics, TAPIR
Funders:
Funding AgencyGrant Number
NSFTGA-ST120025
NSFTG-AST130039
NSFTG-AST140023
NSFPHY-0960291
Alfred P. Sloan FoundationUNSPECIFIED
NASANNX14AH35G
NSFAST-1411920
NSFAST-1455342
Caltech-Carnegie FellowshipUNSPECIFIED
Caltech Moore Center for Theoretical Cosmology and PhysicsUNSPECIFIED
Northwestern UniversityUNSPECIFIED
NSFAST-1412836
NSFAST-1517491
NASANNX15AB22G
NASAHST-AR-14293.001-A
NASAHST-GO-14268.022-A
NSFAST-1412153
University of California San DiegoUNSPECIFIED
NASA12-APT12-0183
Simons FoundationUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA)UNSPECIFIED
Subject Keywords:galaxies: abundances, galaxies: evolution, galaxies: formation, cosmology: theory
Record Number:CaltechAUTHORS:20161107-114246249
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20161107-114246249
Official Citation:Xiangcheng Ma, Philip F. Hopkins, Andrew R. Wetzel, Evan N. Kirby, Daniel Anglés-Alcázar, Claude-André Faucher-Giguère, Dušan Kereš, Eliot Quataert; The structure and dynamical evolution of the stellar disc of a simulated Milky Way-mass galaxy. Mon Not R Astron Soc 2017; 467 (2): 2430-2444. doi: 10.1093/mnras/stx273
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:71771
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:07 Nov 2016 20:12
Last Modified:17 Aug 2017 20:16

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