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Published November 11, 2014 | Submitted + Published
Journal Article Open

The ATLAS^(3D) Project – XXVIII. Dynamically driven star formation suppression in early-type galaxies

Abstract

We present measurements of the star formation rate (SFR) in the early-type galaxies (ETGs) of the ATLAS^(3D) sample, based on Wide-field Infrared Survey Explorer (WISE) 22 μm and Galaxy Evolution Explorer far-ultraviolet emission. We combine these with gas masses estimated from ^(12)CO and H i data in order to investigate the star formation efficiency (SFE) in a larger sample of ETGs than previously available. We first recalibrate (based on WISE data) the relation between old stellar populations (traced at K_s band) and 22 μm luminosity, allowing us to remove the contribution of 22 μm emission from circumstellar dust. We then go on to investigate the position of ETGs on the Kennicutt–Schmidt (KS) relation. Molecular gas-rich ETGs have comparable star formation surface densities to normal spiral galaxy centres, but they lie systematically offset from the KS relation, having lower SFEs by a factor of ≈2.5 (in agreement with other authors). This effect is driven by galaxies where a substantial fraction of the molecular material is in the rising part of the rotation curve, and shear is high. We show here for the first time that although the number of stars formed per unit gas mass per unit time is lower in ETGs, it seems that the amount of stars formed per free-fall time is approximately constant. The scatter around this dynamical relation still correlates with galaxy properties such as the shape of the potential in the inner regions. This leads us to suggest that dynamical properties (such as shear or the global stability of the gas) may be important second parameters that regulate star formation and cause much of the scatter around star formation relations.

Additional Information

© 2014 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2014 March 19. Received 2014 March 18. In original form 2013 December 18. First published online September 17, 2014. The research leading to these results has received funding from the European Community's Seventh Framework Programme (/FP7/2007-2013/) under grant agreement no. 229517. MC acknowledges support from a Royal Society University Research Fellowship. This work was supported by the rolling grants Astrophysics at Oxford PP/E001114/1 and ST/H002456/1 and visitors grants PPA/V/S/2002/00553, PP/E001564/1 and ST/H504862/1 from the UK Research Councils. RLD acknowledges travel and computer grants from Christ Church, Oxford and support from the Royal Society in the form of a Wolfson Merit Award 502011.K502/jd. RLD is also grateful for support from the Australian Astronomical Observatory Distinguished Visitors programme, the ARC Centre of Excellence for All Sky Astrophysics, and the University of Sydney during a sabbatical visit. SK acknowledges support from the Royal Society Joint Projects grant JP0869822. RMMD is supported by the Gemini Observatory, which is operated by the Association of Universities for Research in Astronomy, Inc., on behalf of the international Gemini partnership of Argentina, Australia, Brazil, Canada, Chile, UK, and USA. TN and MBois acknowledge support from the DFG Cluster of Excellence 'Origin and Structure of the Universe'. MS acknowledges support from a STFC Advanced Fellowship ST/F009186/1. PS is a NWO/Veni fellow. MBois has received, during this research, funding from the European Research Council under the Advanced Grant Programme no. 267399-Momentum. LMY acknowledges support from NSF grant AST-1109803. The authors acknowledge financial support from ESO. This paper is based on observations carried out with the IRAM 30m Telescope and the CARMA interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). Support for CARMA construction was derived from the states of California, Illinois, and Maryland, the James S. McDonnell Foundation, the Gordon and Betty Moore Foundation, the Kenneth T. and Eileen L. Norris Foundation, the University of Chicago, the Associates of the California Institute of Technology, and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement, and by the CARMA partner Universities. This publication also makes use of data products from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration.

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Published - MNRAS-2014-Davis-3427-45.pdf

Submitted - 1403.4850v1.pdf

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August 20, 2023
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