Authors

Cheng Li, Shanghai Astronomical Observatory, China
Enci Wang, Shanghai Astronomical Observatory, China
Lin Lin, Shanghai Astronomical Observatory, China
Matthew A. Bershady, University of Wisconsin - Madison
Kevin Bundy, University of Tokyo, Japan
Christy A. Tremonti, University of Wisconsin - Madison
Ting Xiao, Shanghai Astronomical Observatory, China
Renbin Yan, University of KentuckyFollow
Dmitry Bizyaev, Apache Point Observatory
Michael Blanton, New York University
Sabrina Cales, Yale University
Brian Cherinka, University of Toronto, Canada
Edmond Cheung, University of Tokyo, Japan
Niv Drory, University of California - Santa Cruz
Eric Emsellem, European Southern Observatory, Germany
Hai Fu, University of Iowa
Joseph Gelfand, New York University
David R. Law, University of Toronto, Canada
Lahwai Lin, Academia Sinica, Taiwan
Nick MacDonald, University of Washington
Claudia Maraston, University of Portsmouth, UK
Karen L. Masters, University of Portsmouth, UK
Michael R. Merrifield, University of Nottingham, UK
Kaike Pan, Apache Point Observatory
S. F. Sánchez, Universidad Nacional Autonóma de Mexico, Mexico
Donald P. Schneider, Pennsylvania State University
Daniel Thomas, University of Portsmouth, UK
David Wake, University of Wisconsin - Madison
Lixin Wang, Shanghai Astronomical Observatory, China
Anne-Marie Weijmans, University of St. Andrews, UK
David Wilkinson, University of Portsmouth, UK
Peter Yoachim, University of Washington
Kai Zhang, University of KentuckyFollow
Tiantian Zheng, NYU Abu Dhabi, UAE

Abstract

We present an analysis of the data produced by the MaNGA prototype run (P-MaNGA), aiming to test how the radial gradients in recent star formation histories, as indicated by the 4000 Å break (Dn(4000)), Hδ absorption (EW(HδA)), and Hα emission (EW(Hα)) indices, can be useful for understanding disk growth and star formation cessation in local galaxies. We classify 12 galaxies observed on two P-MaNGA plates as either centrally quiescent (CQ) or centrally star-forming (CSF), according to whether Dn(4000) measured in the central spaxel of each datacube exceeds 1.6. For each spaxel we generate both 2D maps and radial profiles of Dn(4000), EW(HδA), and EW(Hα). We find that CSF galaxies generally show very weak or no radial variation in these diagnostics. In contrast, CQ galaxies present significant radial gradients, in the sense that Dn(4000) decreases, while both EW(HδA) and EW(Hα) increase from the galactic center outward. The outer regions of the galaxies show greater scatter on diagrams relating the three parameters than their central parts. In particular, the clear separation between centrally measured quiescent and star-forming galaxies in these diagnostic planes is largely filled in by the outer parts of galaxies whose global colors place them in the green valley, supporting the idea that the green valley represents a transition between blue-cloud and red-sequence phases, at least in our small sample. These results are consistent with a picture in which the cessation of star formation propagates from the center of a galaxy outward as it moves to the red sequence.

Document Type

Article

Publication Date

5-10-2015

Notes/Citation Information

Published in The Astrophysical Journal, v. 804, no. 2, article 125, p. 1-19.

© 2015. The American Astronomical Society. All rights reserved.

Reproduced by permission of the AAS.

Digital Object Identifier (DOI)

http://dx.doi.org/10.1088/0004-637X/804/2/125

Funding Information

C.L. acknowledges the support of the 100 Talents Program of Chinese Academy of Sciences (CAS). This work is supported by NSFC (11173045,11233005,11325314,11320101002), by the Strategic Priority Research Program "The Emergence of Cosmological Structures" of CAS (grant No. XDB09000000), and by World Premier International Research Center Initiative (WPI Initiative), MEXT, Japan. . . . Funding for SDSS-III and SDSS-IV has been provided by the Alfred P. Sloan Foundation and Participating Institutions. Additional funding for SDSS-III comes from the National Science Foundation and the U.S. Department of Energy Office of Science. Further information about both projects is available at www.sdss3.org.

SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions in both collaborations. In SDSS-III these include 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.

The Participating Institutions in SDSS-IV are Carnegie Mellon University, Colorado University, Boulder, Harvard-Smithsonian Center for Astrophysics Participation Group, Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the universe, Max-Planck-Institut fuer Astrophysik (MPA Garching), Max-Planck-Institut fuer Extraterrestrische Physik (MPE), Max-Planck-Institut fuer Astronomie (MPIA Heidelberg), National Astronomical Observatory of China, New Mexico State University, New York University, The Ohio State University, Penn State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, University of Portsmouth, University of Utah, University of Wisconsin, and Yale University.

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