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The mass assembly history of field galaxies: Detection of an evolving mass limit for starforming galaxies

Bundy, Kevin and Ellis, Richard S. and Conselice, Christopher J. and Taylor, James E. and Cooper, Michael C. and Willmer, Christopher N. A. and Weiner, Benjamin J. and Coil, Alison L. and Noeske, Kai G. and Eisenhardt, Peter R. M. (2006) The mass assembly history of field galaxies: Detection of an evolving mass limit for starforming galaxies. Astrophysical Journal, 651 (1). pp. 120-141. ISSN 0004-637X.

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We characterize the mass-dependent evolution of more than 8000 galaxies using spectroscopic redshifts from the DEEP2 Galaxy Redshift Survey in the range 0.4 < z < 1.4 and stellar masses calculated from K-band photometry obtained at Palomar Observatory. This sample spans more than 1.5 deg^2 in four independent fields. Using rest-frame U - B color and [O II] equivalent widths, we distinguish star-forming from passive populations in order to explore the nature of "downsizing"—a pattern in which the sites of active star formation shift from high-mass galaxies at early times to lower mass systems at later epochs. We identify a mass limit, M_Q, above which star formation appears to be quenched and show that the physical mechanisms responsible for downsizing can thus be empirically quantified by charting the evolution in this threshold mass. We find that M_Q decreases with time by a factor of ~3 across our redshift range according to M_Q α (1 + z)^(3.5). To further constrain possible quenching mechanisms, we investigate how downsizing depends on local galaxy environment using the projected third-nearest-neighbor statistic D_(p,3). For the majority of galaxies near the median density, there is no significant correlation between downsizing and environment. However, a trend is observed in the comparison between environments that are more than 3 times overdense or underdense relative to the median. Here, downsizing appears accelerated in overdense regions that host higher numbers of massive, early-type galaxies as compared to the underdense regions. Our results significantly constrain recent suggestions for the origin of downsizing and indicate that the process for quenching star formation must, primarily, be internally driven

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Bundy, Kevin0000-0001-9742-3138
Ellis, Richard S.0000-0001-7782-7071
Conselice, Christopher J.0000-0003-1949-7638
Additional Information:© 2006 The American Astronomical Society. Received 2005 December 18; accepted 2006 June 28. We are very grateful to the referee, Jarle Brinchmann, for very useful comments and suggestions that have strengthened this work. We also thank Nick Kaiser for generously providing the optical photometry in this paper. The Palomar Survey was supported by NSF grant AST 03-07859 and NASA STScI grant HST-AR-09920.01-A. Support from National Science Foundation grants 00-71198 to UCSC and AST 00-71048 to UCB is also gratefully acknowledged. A. L. C. is supported by NASA through Hubble Fellowship grant HF-01182.01-A, awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., for NASA, under contract NAS 5-26555.We wish to recognize and acknowledge the highly significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. It is a privilege to be given the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
NSFAST 03-07859
NSFAST 00-71198
NSFAST 00-71048
NASA Hubble FellowshipHF-01182.01-A
NASANAS 5-26555
Subject Keywords:cosmology: observations; galaxies: evolution; galaxies: formation
Issue or Number:1
Record Number:CaltechAUTHORS:20110218-093519381
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Official Citation:The Mass Assembly History of Field Galaxies: Detection of an Evolving Mass Limit for Star-Forming Galaxies Kevin Bundy, Richard S. Ellis, Christopher J. Conselice, James E. Taylor, Michael C. Cooper, Christopher N. A. Willmer, Benjamin J. Weiner, Alison L. Coil, Kai G. Noeske, and Peter R. M. Eisenhardt doi: 10.1086/507456
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:22376
Deposited By: Ruth Sustaita
Deposited On:18 Feb 2011 19:20
Last Modified:26 Nov 2019 11:15

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