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Title: Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies

Abstract

We utilize zoom-in cosmological simulations to study the nature of violent disc instability in clumpy galaxies at high redshift, z = 1–5. Our simulated galaxies are not in the ideal state assumed in Toomre instability, of linear fluctuations in an isolated, uniform, rotating disc. There, instability is characterized by a Q parameter below unity, and lower when the disc is thick. Instead, the high-redshift discs are highly perturbed. Over long periods they consist of non-linear perturbations, compact massive clumps and extended structures, with new clumps forming in interclump regions. This is while the galaxy is subject to frequent external perturbances. We compute the local, two-component Q parameter for gas and stars, smoothed on a ~1 kpc scale to capture clumps of 10 8-9 M . The Q < 1 regions are confined to collapsed clumps due to the high surface density there, while the interclump regions show Q significantly higher than unity. Tracing the clumps back to their relatively smooth Lagrangian patches, we find that Q prior to clump formation typically ranges from unity to a few. This is unlike the expectations from standard Toomre instability. We discuss possible mechanisms for high- Q clump formation, e.g. rapid turbulence decay leadingmore » to small clumps that grow by mergers, non-axisymmetric instability, or clump formation induced by non-linear perturbations in the disc. Alternatively, the high- Q non-linear VDI may be stimulated by the external perturbations such as mergers and counter-rotating streams. The high Q may represent excessive compressive modes of turbulence, possibly induced by tidal interactions.« less

Authors:
 [1];  [1];  [1];  [2];  [3];  [4]
  1. Hebrew Univ. of Jerusalem (Israel). Racah Inst. of Physics
  2. Consejo Superior de Investigaciones Cientificas (CSIC), Madrid (Spain). Centro de Astrobiologia; Univ. Autonoma de Madrid (Spain). Astro-UAM
  3. Univ. Paris-Saclay, Gif-sur-Yvette (France). Lab. AIM
  4. Univ. of California, Santa Cruz, CA (United States). Dept. of Physics
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory-National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE
OSTI Identifier:
1542105
Resource Type:
Accepted Manuscript
Journal Name:
Monthly Notices of the Royal Astronomical Society
Additional Journal Information:
Journal Volume: 456; Journal Issue: 2; Journal ID: ISSN 0035-8711
Publisher:
Royal Astronomical Society
Country of Publication:
United States
Language:
English
Subject:
instabilities – methods: numerical – galaxies: formation – galaxies: kinematics and dynamics

Citation Formats

Inoue, Shigeki, Dekel, Avishai, Mandelker, Nir, Ceverino, Daniel, Bournaud, Frédéric, and Primack, Joel. Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies. United States: N. p., 2015. Web. doi:10.1093/mnras/stv2793.
Inoue, Shigeki, Dekel, Avishai, Mandelker, Nir, Ceverino, Daniel, Bournaud, Frédéric, & Primack, Joel. Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies. United States. doi:10.1093/mnras/stv2793.
Inoue, Shigeki, Dekel, Avishai, Mandelker, Nir, Ceverino, Daniel, Bournaud, Frédéric, and Primack, Joel. Wed . "Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies". United States. doi:10.1093/mnras/stv2793. https://www.osti.gov/servlets/purl/1542105.
@article{osti_1542105,
title = {Non-linear violent disc instability with high Toomre's Q in high-redshift clumpy disc galaxies},
author = {Inoue, Shigeki and Dekel, Avishai and Mandelker, Nir and Ceverino, Daniel and Bournaud, Frédéric and Primack, Joel},
abstractNote = {We utilize zoom-in cosmological simulations to study the nature of violent disc instability in clumpy galaxies at high redshift, z = 1–5. Our simulated galaxies are not in the ideal state assumed in Toomre instability, of linear fluctuations in an isolated, uniform, rotating disc. There, instability is characterized by a Q parameter below unity, and lower when the disc is thick. Instead, the high-redshift discs are highly perturbed. Over long periods they consist of non-linear perturbations, compact massive clumps and extended structures, with new clumps forming in interclump regions. This is while the galaxy is subject to frequent external perturbances. We compute the local, two-component Q parameter for gas and stars, smoothed on a ~1 kpc scale to capture clumps of 108-9 M⊙. The Q < 1 regions are confined to collapsed clumps due to the high surface density there, while the interclump regions show Q significantly higher than unity. Tracing the clumps back to their relatively smooth Lagrangian patches, we find that Q prior to clump formation typically ranges from unity to a few. This is unlike the expectations from standard Toomre instability. We discuss possible mechanisms for high-Q clump formation, e.g. rapid turbulence decay leading to small clumps that grow by mergers, non-axisymmetric instability, or clump formation induced by non-linear perturbations in the disc. Alternatively, the high-Q non-linear VDI may be stimulated by the external perturbations such as mergers and counter-rotating streams. The high Q may represent excessive compressive modes of turbulence, possibly induced by tidal interactions.},
doi = {10.1093/mnras/stv2793},
journal = {Monthly Notices of the Royal Astronomical Society},
number = 2,
volume = 456,
place = {United States},
year = {2015},
month = {12}
}

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