A Massive Quiescent Galaxy Confirmed in a Protocluster at z = 3.09

Creators: Kubo, Mariko; Umehata, Hideki; Matsuda, Yuichi; Kajisawa, Masaru; Steidel, Charles C.; Yamada, Toru; Tanaka, Ichi; Hatsukade, Bunyo; Tamura, Yoichi; Nakanishi, Kouichiro; Kohno, Kotaro; Lee, Kianhong; Matsuda, Keiichi

Abstract

We report a massive quiescent galaxy at z_(spec) = 3.0922^(+0.008)_(−0.004) spectroscopically confirmed at a protocluster in the SSA22 field by detecting the Balmer and Ca II absorption features with the multi-object spectrometer for infrared exploration on the Keck I telescope. This is the most distant quiescent galaxy confirmed in a protocluster to date. We fit the optical to mid-infrared photometry and spectrum simultaneously with spectral energy distribution (SED) models of parametric and nonparametric star formation histories (SFHs). Both models fit the observed SED well and confirm that this object is a massive quiescent galaxy with a stellar mass of log(M⋆/M_⊙) = 11.26^(+0.03)_(−0.04) and 11.54^(+0.03)_(−0.00), and a star formation rate of SFR/M_⊙ yr⁻¹ < 0.3 and = 0.01^(+0.03)_(−0.01) for parametric and nonparametric models, respectively. The SFH from the former modeling is described as an instantaneous starburst whereas that of the latter modeling is longer-lived, but both models agree with a sudden quenching of the star formation at ∼0.6 Gyr ago. This massive quiescent galaxy is confirmed in an extremely dense group of galaxies predicted as a progenitor of a brightest cluster galaxy formed via multiple mergers in cosmological numerical simulations. We discover three new plausible [O III]λ5007 emitters at 3.0791 ≤ z_(spec) ≤ 3.0833 serendipitously detected around the target. Two of them just between the target and its nearest massive galaxy are possible evidence of their interactions. They suggest the future great size and stellar mass evolution of this massive quiescent galaxy via mergers.

Additional Information

© 2021. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2021 January 9; revised 2021 June 17; accepted 2021 June 18; published 2021 September 16. We thank the anonymous referee for a number of useful suggestions. This work is supported by JSPS KAKENHI grant Numbers 20K14530 (MK), 17K14252, 20H01953 (HU), 17KK0098 (YM), 19K0397 (KN), and 17H06130 (KK). The spectroscopic data 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 observations were carried out within the framework of Subaru-Keck/Subaru-Gemini time exchange program, which is operated by the National Astronomical Observatory of Japan. The K_s-band image was collected with nuMOIRCS at Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. We are honored and grateful for the opportunity of observing the universe from Maunakea, which has cultural, historical, and natural significance in Hawaii. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2013.1.00162.S, ADS/JAO.ALMA#2017.1.01332.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada), MOST 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. The F814W-band image is based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the data archive at the Space Telescope Science Institute. STScI is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555.

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