The Star-Formation History of BCGs to z = 1.8 from the SpARCS/SWIRE Survey: Evidence for significant in-situ star formation at high-redshift
Abstract
We present the results of an MIPS-24 μm study of the brightest cluster galaxies (BCGs) of 535 high-redshift galaxy clusters. The clusters are drawn from the Spitzer Adaptation of the Red-Sequence Cluster Survey, which effectively provides a sample selected on total stellar mass, over 0.2 < z < 1.8 within the Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey fields. Twenty percent, or 106 clusters, have spectroscopically confirmed redshifts, and the rest have redshifts estimated from the color of their red sequence. A comparison with the public SWIRE images detects 125 individual BCGs at 24 μm ≳ 100 μJy, or 23%. The luminosity-limited detection rate of BCGs in similar richness clusters (N_(gal) > 12) increases rapidly with redshift. Above z ~ 1, an average of ~20% of the sample have 24 μm inferred infrared luminosities of L_(IR) > 10^(12) L_⊙, while the fraction below z ~ 1 exhibiting such luminosities is <1%. The Spitzer-IRAC colors indicate the bulk of the 24 μm detected population is predominantly powered by star formation, with only 7/125 galaxies lying within the color region inhabited by active galactic nuclei (AGNs). Simple arguments limit the star formation activity to several hundred million years and this may therefore be indicative of the timescale for AGN feedback to halt the star formation. Below redshift z ~ 1, there is not enough star formation to significantly contribute to the overall stellar mass of the BCG population, and therefore BCG growth is likely dominated by dry mergers. Above z ~ 1, however, the inferred star formation would double the stellar mass of the BCGs and is comparable to the mass assembly predicted by simulations through dry mergers. We cannot yet constrain the process driving the star formation for the overall sample, though a single object studied in detail is consistent with a gas-rich merger.
Additional Information
© 2015 American Astronomical Society. Received 2015 March 13; accepted 2015 August 19; published 2015 November 20. Funding for PRIMUS is provided by NSF (AST-0607701, AST-0908246, AST-0908442, AST-0908354) and NASA (Spitzer-1356708, 08-ADP08-0019, NNX09AC95G). T.M.A.W. acknowledges the support of an NSERC Discovery Grant. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. 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. Financial support for this work was provided by NASA through programs GO-13306, GO-13677, GO-13747, GO-13845, and GO-14327 from the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS 5-26555. Facilities: Spitzer Space Telescope (MIPS; IRAC) - , Magellan (IMACS) - , CTIO - , CFHT - Canada-France-Hawaii TelescopeAttached Files
Published - Webb_2015.pdf
Submitted - 1508.07302v1.pdf
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Additional details
- Eprint ID
- 63140
- Resolver ID
- CaltechAUTHORS:20151222-105600116
- AST-0607701
- NSF
- AST-0908246
- NSF
- AST-0908442
- NSF
- AST-0908354
- NSF
- Spitzer-1356708
- NASA
- 08-ADP08-0019
- NASA
- NNX09AC95G
- NASA
- Natural Sciences and Engineering Research Council of Canada (NSERC)
- Alfred P. Sloan Foundation
- GO-13306
- NASA
- GO-13677
- NASA
- GO-13747
- NASA
- GO-13845
- NASA
- GO-14327
- NASA
- Space Telescope Science Institute
- NAS 5-26555
- NASA
- Created
-
2015-12-22Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field
- Caltech groups
- Infrared Processing and Analysis Center (IPAC)