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On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Protoclusters at z ≈ 2.0–2.5

Zavala, J. A. and Casey, C. M. and Scoville, N. and Champagne, J. B. and Chiang, Y. and Dannerbauer, H. and Drew, P. and Fu, H. and Spilker, J. and Spitler, L. and Tran, K. V. and Treister, E. and Toft, S. (2019) On the Gas Content, Star Formation Efficiency, and Environmental Quenching of Massive Galaxies in Protoclusters at z ≈ 2.0–2.5. Astrophysical Journal, 887 (2). Art. No. 183. ISSN 1538-4357.

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We present ALMA Band 6 (ν = 233 GHz, λ = 1.3 mm) continuum observations toward 68 "normal" star-forming galaxies within two Coma-like progenitor structures at z = 2.10 and 2.47, from which ISM masses are derived, providing the largest census of molecular gas mass in overdense environments at these redshifts. Our sample comprises galaxies with a stellar mass range of 1 × 10⁹ M_⊙–4 × 10¹¹ M_⊙ with a mean M_★ ≈ 6 × 10¹⁰ M_⊙. Combining these measurements with multiwavelength observations and spectral energy distribution modeling, we characterize the gas mass fraction and the star formation efficiency, and infer the impact of the environment on galaxies' evolution. Most of our detected galaxies (≳70%) have star formation efficiencies and gas fractions similar to those found for coeval field galaxies and in agreement with the field scaling relations. However, we do find that the protoclusters contain an increased fraction of massive, gas-poor galaxies, with low gas fractions (f_(gas) ≾ 6%–10%) and red rest-frame ultraviolet/optical colors typical of post-starburst and passive galaxies. The relatively high abundance of passive galaxies suggests an accelerated evolution of massive galaxies in protocluster environments. The large fraction of quenched galaxies in these overdense structures also implies that environmental quenching takes place during the early phases of cluster assembly, even before virialization. From our data, we derive a quenching efficiency of ϵ_q ≈ 0.45 and an upper limit on the quenching timescale of τ_q < 1 Gyr.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Zavala, J. A.0000-0002-7051-1100
Casey, C. M.0000-0002-0930-6466
Scoville, N.0000-0002-0438-3323
Champagne, J. B.0000-0002-6184-9097
Chiang, Y.0000-0001-6320-261X
Dannerbauer, H.0000-0001-7147-3575
Drew, P.0000-0003-3627-7485
Fu, H.0000-0001-9608-6395
Spilker, J.0000-0003-3256-5615
Spitler, L.0000-0001-5185-9876
Tran, K. V.0000-0001-9208-2143
Treister, E.0000-0001-7568-6412
Toft, S.0000-0003-3631-7176
Additional Information:© 2019. The American Astronomical Society. Received 2019 May 28; revised 2019 October 7; accepted 2019 October 29; published 2019 December 18. We thank Anthony Remijan and Jeremy Thorley from the North American ALMA Science Center (NAASC) for their help with data reduction and retrieval. J.A.Z. and C.M.C. thank the University of Texas at Austin College of Natural Sciences for support, in addition to NSF grant AST-1714528 and AST-1814034. E.T. acknowledges support from FONDECYT Regular 1160999, CONICYT PIA ACT172033 and Basal-CATA PFB-06/2007 and AFB170002 grants. H.D. acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2014 Ramón y Cajal program RYC-2014-15686 and AYA2017-84061-P, the latter one cofinanced by FEDER (European Regional Development Funds). S.T. acknowledges support from the European Research Council (ERC) Consolidator Grant funding scheme (project ConTExt, grant No. 648179). The Cosmic Dawn Center is funded by the Danish National Research Foundation. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2016.1.00646.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ.
Group:Astronomy Department
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1160999
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)ACT172033
Ramón y Cajal ProgrammeRYC-2014-15686
Ministerio de Ciencia, Innovación y Universidades (MICIU)AYA2017-84061-P
Fondo Europeo de Desarrollo Regional (FEDER)UNSPECIFIED
European Research Council (ERC)648179
Danish National Research FoundationUNSPECIFIED
Subject Keywords:Quenched galaxies ; Submillimeter astronomy
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Quenched galaxies (2016); Submillimeter astronomy (1647)
Record Number:CaltechAUTHORS:20191219-112735357
Persistent URL:
Official Citation:J. A. Zavala et al 2019 ApJ 887 183
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100379
Deposited By: George Porter
Deposited On:20 Dec 2019 15:48
Last Modified:20 Dec 2019 15:48

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