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SDSS-IV MaNGA: constraints on the conditions for star formation in galaxy discs

Stark, David V. and Bundy, Kevin A and Orr, Matthew E. and Hopkins, Philip F. and Westfall, Kyle and Bershady, Matthew and Li, Cheng and Bizyaev, Dmitry and Masters, Karen L. and Weijmans, Anne-Marie and Lacerna, Ivan and Thomas, Daniel and Drory, Niv and Yan, Renbin and Zhang, Kai (2018) SDSS-IV MaNGA: constraints on the conditions for star formation in galaxy discs. Monthly Notices of the Royal Astronomical Society, 474 (2). pp. 2323-2333. ISSN 0035-8711.

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Regions of disc galaxies with widespread star formation tend to be both gravitationally unstable and self-shielded against ionizing radiation, whereas extended outer discs with little or no star formation tend to be stable and unshielded on average. We explore what drives the transition between these two regimes, specifically whether discs first meet the conditions for self-shielding (parametrized by dust optical depth, τ) or gravitational instability (parametrized by a modified version of Toomre's instability parameters, Qthermal, which quantifies the stability of a gas disc that is thermally supported at T = 104 K). We first introduce a new metric formed by the product of these quantities, Qthermalτ, which indicates whether the conditions for disc instability or self-shielding are easier to meet in a given region of a galaxy, and we discuss how Qthermalτ can be constrained even in the absence of direct gas information. We then analyse a sample of 13 galaxies with resolved gas measurements and find that on average galaxies will reach the threshold for disc instabilities (Qthermal < 1) before reaching the threshold for self-shielding (τ > 1). Using integral field spectroscopic observations of a sample of 236 galaxies from the Mapping Nearby Galaxies at APO (MaNGA) survey, we find that the value of Qthermalτ in star-forming discs is consistent with similar behaviour. These results support a scenario where disc fragmentation and collapse occurs before self-shielding, suggesting that gravitational instabilities are the primary condition for widespread star formation in galaxy discs. Our results support similar conclusions based on recent galaxy simulations.

Item Type:Article
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URLURL TypeDescription Paper
Orr, Matthew E.0000-0003-1053-3081
Hopkins, Philip F.0000-0003-3729-1684
Li, Cheng0000-0002-8280-3119
Additional Information:© 2017 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 October 30. Received 2017 October 9; in original form 2017 July 27. We thank our anonymous referee for constructive feedback that greatly improved this work. We would also like to thank Christy Tremonti and Eric Emsellem for useful discussions. This work was supported by World Premier International Research Centre Initiative (WPI Initiative), MEXT, Japan. MB acknowledges NSF-AST-1517006. A-MW acknowledges support of a Leverhulme Trust Early Career Fellowship. DB acknowledges support from RSF grant RSCF-14-50-00043. MEO was supported by the National Science Foundation Graduate Research Fellowship under Grant No. 1144469. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the US Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the centre for High-Performance Computing at the University of Utah. The SDSS web site is SDSS-IV is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, the Chilean Participation Group, the French Participation Group, Harvard-Smithsonian Centre for Astrophysics, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU)/University of Tokyo, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA, Heidelberg), Max-Planck-Institut für Astrophysik (MPA, Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatário Nacional/MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University.
Funding AgencyGrant Number
Ministry of Education, Culture, Sports, Science and Technology (MEXT)UNSPECIFIED
Leverhulme TrustUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
Alfred P. Sloan FoundationUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Subject Keywords:galaxies: star formation
Record Number:CaltechAUTHORS:20180301-134435945
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Official Citation:David V Stark, Kevin A Bundy, Matthew E Orr, Philip F Hopkins, Kyle Westfall, Matthew Bershady, Cheng Li, Dmitry Bizyaev, Karen L Masters, Anne-Marie Weijmans, Ivan Lacerna, Daniel Thomas, Niv Drory, Renbin Yan, Kai Zhang; SDSS-IV MaNGA: constraints on the conditions for star formation in galaxy discs, Monthly Notices of the Royal Astronomical Society, Volume 474, Issue 2, 21 February 2018, Pages 2323–2333,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85043
Deposited By: Ruth Sustaita
Deposited On:01 Mar 2018 23:27
Last Modified:01 Mar 2018 23:27

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