Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 21, 2017 | Submitted + Published
Journal Article Open

Chronos and KAIROS: MOSFIRE observations of post-starburst galaxies in z ∼ 1 clusters and groups


We present an exploration of ∼500 spectroscopically confirmed galaxies in and around two large-scale structures (LSSs) at z ∼ 1 drawn from the Observations of Redshift Evolution in Large Scale Environments survey, an ongoing, wide-field photometric and spectroscopic campaign targeting a large ensemble of LSSs at 0.6 < z < 1.3. A sub-sample of these galaxies (∼150) was targeted for the initial phase of a near-infrared MOSFIRE spectroscopic campaign investigating the differences in selections of galaxies that had recently ended a burst of star formation and/or had rapidly quenched (i.e. post-starburst/K+A galaxies). Selection with MOSFIRE utilizing the H α and [N II] emission features resulted in a post-starburst sample more than double that selected by traditional z ∼ 1 (observed-frame optical) methods even after the removal of the relatively large fraction of dusty starburst galaxies selected through traditional methods. While the traditional post-starburst fraction increased with increasing global density, the MOSFIRE-selected post-starburst fraction was found to be constant across field, group, and cluster environments. However, this fraction computed relative to the number of star-forming galaxies was observed to elevate in the cluster environment. Post-starbursts selected with MOSFIRE exhibited moderately strong [O II] emission originating from activity other than star formation. Such galaxies, termed K+A with ImposteR [O II]-derived Star formation (KAIROS) galaxies, were found to be younger than and likely undergoing feedback absent or diminished in their optically selected counterparts. A comparison between the environments of the two types of post-starbursts suggested a picture in which the evolution of a post-starburst galaxy is considerably different in cluster environments than in the more rarefied environments of a group or the field.

Additional Information

© 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2017 June 21; Received 2017 June 21; in original form 2016 July 29; Published: 26 June 2017. This material is based upon the work supported by the National Science Foundation under Grant No. 1411943. Part of the work presented herein is supported by NASA Grant Number NNX15AK92G. BCL thanks Nelson Cheung and Stephen Lampa for laying the foundation for this study and for looking through thousands of DEIMOS spectra for little glory and even less pay. BCL gratefully acknowledges Romain Thomas for discussions and guidance related to age estimates and Alison Mansheim and Lu Shen for discussions that improved the paper. We also thank the anonymous referee for helpful and careful guidance. This study is based, in part, on data collected at the Subaru Telescope and obtained from the SMOKA, which is operated by the Astronomy Data Center, National Astronomical Observatory of Japan. This work is based, in part, on observations made with the Spitzer SpaceTelescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. UKIRT is supported by NASA and operated under an agreement among the University of Hawaii, the University of Arizona, and Lockheed Martin Advanced Technology Center; operations are enabled through the cooperation of the East Asian Observatory. When the data reported here were acquired, UKIRT was operated by the Joint Astronomy Centre on behalf of the Science and Technology Facilities Council of the U.K. This study is also based, in part, on observations obtained with WIRCam, a joint project of CFHT, Taiwan, Korea, Canada, France, and the Canada-France-Hawaii Telescope, which is operated by the National Research Council (NRC) of Canada, the Institut National des Sciences de l'Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawai'i. The scientific results reported in this article are based in part on observations made by the Chandra X-ray Observatory and data obtained from the Chandra Data Archive. The spectrographic data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation. We wish to thank the indigenous Hawaiian community for allowing us to be guests on their sacred mountain, a privilege, without which, this work would not have been possible. We are most fortunate to be able to conduct observations from this site.

Attached Files

Published - stx1579.pdf

Submitted - 1608.00973.pdf


Files (2.5 MB)
Name Size Download all
1.5 MB Preview Download
1.0 MB Preview Download

Additional details

August 19, 2023
October 17, 2023