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Published April 21, 2015 | Published + Supplemental Material + Submitted
Journal Article Open

The ATLAS^(3D) Project – XXX. Star formation histories and stellar population scaling relations of early-type galaxies


We present the stellar population content of early-type galaxies from the ATLAS^(3D) survey. Using spectra integrated within apertures covering up to one effective radius, we apply two methods: one based on measuring line-strength indices and applying single stellar population (SSP) models to derive SSP-equivalent values of stellar age, metallicity, and alpha enhancement; and one based on spectral fitting to derive non-parametric star formation histories, mass-weighted average values of age, metallicity, and half-mass formation time-scales. Using homogeneously derived effective radii and dynamically determined galaxy masses, we present the distribution of stellar population parameters on the Mass Plane (M_(JAM), σ_e, R^(maj)_e), showing that at fixed mass, compact early-type galaxies are on average older, more metal-rich, and more alpha-enhanced than their larger counterparts. From non-parametric star formation histories, we find that the duration of star formation is systematically more extended in lower mass objects. Assuming that our sample represents most of the stellar content of today's local Universe, approximately 50 per cent of all stars formed within the first 2 Gyr following the big bang. Most of these stars reside today in the most massive galaxies (>10^(10.5) M⊙), which themselves formed 90 per cent of their stars by z ∼ 2. The lower mass objects, in contrast, have formed barely half their stars in this time interval. Stellar population properties are independent of environment over two orders of magnitude in local density, varying only with galaxy mass. In the highest density regions of our volume (dominated by the Virgo cluster), galaxies are older, alpha-enhanced, and have shorter star formation histories with respect to lower density regions.

Additional Information

© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 January 15. Received 2015 January 15; in original form 2014 October 14. First published online March 11, 2015. We thank the referee, Daniel Thomas, for a constructive report, which helped improve this paper. RMcD would like to thank Inger Jørgensen for a careful reading of early drafts of this paper, and Ricardo Schiavon for numerous instructive discussions. RMcD and RLD gratefully acknowledge the hospitality of the ESO visitor programme during the preparation of this work. 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 visitor 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. TN acknowledges support from the DFG Cluster of Excellence Origin and Structure of the Universe. MS acknowledges support from an STFC Advanced Fellowship ST/F009186/1. TAD acknowledges the support provided by an ESO fellowship. 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. The authors acknowledge financial support from ESO. SK acknowledges support from the Royal Society Joint Projects Grant JP0869822. NS acknowledges support of Australian Research Council grant DP110103509. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the US Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/. SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University.

Attached Files

Published - MNRAS-2015-McDermid-3484-513.pdf

Submitted - 1501.03723v1.pdf

Supplemental Material - McDermid2015_Atlas3D_Paper30_Table1.txt

Supplemental Material - McDermid2015_Atlas3D_Paper30_Table2.txt

Supplemental Material - McDermid2015_Atlas3D_Paper30_Table3.txt

Supplemental Material - McDermid2015_Atlas3D_Paper30_Table4.txt


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August 22, 2023
October 23, 2023