Evolution of Environmental Quenching Timescales to z ∼ 1.6: Evidence for Dynamically Driven Quenching of the Cluster Galaxy Population

Creators: Foltz, R.; Wilson, G.; Muzzin, A.; Cooper, M. C.; Nantais, J.; van der Burg, R. F. J.; Cerulo, P.; Chan, J.; Fillingham, S. P.; Surace, J.; Webb, T.; Noble, A.; Lacy, M.; McDonald, M.; Rudnick, G.; Lidman, C.; Demarco, R.; Hlavacek-Larrondo, J.; Yee, H. K. C.; Perlmutter, S.; Hayden, B.

Abstract

Using a sample of four galaxy clusters at 1.35 < z < 1.65 and 10 galaxy clusters at 0.85 < z < 1.35, we measure the environmental quenching timescale, t Q, corresponding to the time required after a galaxy is accreted by a cluster for it to fully cease star formation. Cluster members are selected by a photometric-redshift criterion, and categorized as star-forming, quiescent, or intermediate according to their dust-corrected rest-frame colors and magnitudes. We employ a "delayed-then-rapid" quenching model that relates a simulated cluster mass accretion rate to the observed numbers of each type of galaxy in the cluster to constrain t_Q. For galaxies of mass M* ≳ 10^(10.5) M⊙, we find a quenching timescale of t_Q = 1.1^(+0.3)_(-0.3) Gyr in the z ~ 1.5 cluster sample, and t_Q = 1.3^(+0.3)_(-0.3) Gyr at z ~ 1. Using values drawn from the literature, we compare the redshift evolution of t_Q to timescales predicted for different physical quenching mechanisms. We find t_Q to depend on host halo mass such that quenching occurs over faster timescales in clusters relative to groups, suggesting that properties of the host halo are responsible for quenching high-mass galaxies. Between z = 0 and z = 1.5, we find that t_Q evolves faster than the molecular gas depletion timescale and slower than an estimated star formation rate-outflow timescale, but is consistent with the evolution of the dynamical time. This suggests that environmental quenching in these galaxies is driven by the motion of satellites relative to the cluster environment, although due to uncertainties in the atomic gas budget at high redshift, we cannot rule out quenching due to simple gas depletion.

Additional Information

© 2018 The American Astronomical Society. Received 2018 February 14; revised 2018 July 22; accepted 2018 August 2; published 2018 October 23. We thank Michael Balogh for his advice and contributions to this work prior to its publication. We thank Matteo Fossati for providing the measurements shown in Figure 5. This work is supported by the National Science Foundation through grant AST-1517863, by HST program numbers GO-13306, 13845, 13747, 13677/14327 and 15294, and by grant number 80NSSC17K0019 issued through the NASA Astrophysics Data Analysis Program (ADAP). Support for program numbers GO-13306, 13845, 13747, 13677/14327 and 15294 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. J.N. is supported by Universidad Andres Bello internal research grant DI-18-17/RG. Support for M.C.C. was provided in part by NSF grant AST-1518257 as well as by NASA through grants AR-13242 and AR-14289 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555. P.C. acknowledges the support of the FONDECYT postdoctoral research grant no 3160375. Data presented herein were obtained using the UCI Remote Observing Facility, made possible by a generous gift from John and Ruth Ann Evans. Some of the 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. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Maunakea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.

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