GOODS-ALMA: The slow downfall of star formation in z = 2–3 massive galaxies

¹ AIM, CEA, CNRS, Université Paris-Saclay, Université Paris Diderot, Sorbonne Paris Cité, 91191 Gif-sur-Yvette, France
² Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
e-mail: m.franco@herts.ac.uk
³ School of Astronomy and Space Science, Nanjing University, Nanjing 210093, PR China
⁴ Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, Nanjing 210093, PR China
⁵ Argelander-Institut für Astronomie, Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
⁶ Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH, UK
⁷ Aix Marseille Université, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, Marseille, France
⁸ Community Science and Data Center/NSF’s NOIRLab, 950 N. Cherry Ave., Tucson, AZ 85719, USA
⁹ Department of Astronomy, Universidad de Concepción, Casilla 160-C, Concepción, Chile
¹⁰ Departamento de Astronomía, Facultad de Ciencias Físicas y Matemáticas, Universidad de Concepción, Concepción, Chile
¹¹ Cosmic Dawn Center at the Niels Bohr Institute, University of Copenhagen and DTU-Space, Technical University of Denmark, Kgs. Lyngby, Denmark
¹² DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, 2800 Kgs. Lyngby, Denmark
¹³ Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
¹⁴ Institute for Astronomy, Astrophysics, Space Applications and Remote Sensing, National Observatory of Athens, 15236 Athens, Greece
¹⁵ Centre for Extragalactic Astronomy, Department of Physics, Durham University, Durham DH1 3LE, UK
¹⁶ Institute of Astronomy, University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
¹⁷ Department of Physics and Astronomy, The University of Sheffield, Hounsfield Road, Sheffield S3 7RH, UK
¹⁸ Astronomy Centre, Department of Physics and Astronomy, University of Sussex, Brighton BN1 9QH, UK
¹⁹ Univ. Lyon, Univ. Lyon1, ENS de Lyon, CNRS, Centre de Recherche Astrophysique de Lyon (CRAL) UMR5574, 69230 Saint-Genis-Laval, France
²⁰ Hiroshima Astrophysical Science Center, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526, Japan
²¹ Department of Physics, Anhui Normal University, Wuhu, Anhui 241000, PR China
²² Infrared Processing and Analysis Center, MS314-6, California Institute of Technology, Pasadena, CA 91125, USA
²³ Max-Planck-Institut für Extraterrestrische Physik (MPE), Giessenbachstr.1, 85748 Garching, Germany
²⁴ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²⁵ Department of Astronomy, The University of Texas at Austin, Austin, TX 78712, USA
²⁶ Astronomy Department, University of Massachusetts, Amherst, MA 01003, USA
²⁷ National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
²⁸ SOKENDAI (The Graduate University for Advanced Studies), 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan
²⁹ Institute of Astronomy & Astrophysics, Academia Sinica, Taipei 10617, Taiwan
³⁰ Institute of Astronomy, Graduate School of Science, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015, Japan
³¹ Astronomy Unit, Department of Physics, University of Trieste, Via Tiepolo 11, 34131 Trieste, Italy
³² Fakultät für Physik der Ludwig-Maximilians-Universität, 81679 München, Germany
³³ Department of Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
³⁴ George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University, College Station, TX 77843-4242, USA
³⁵ Department of Physics, Faculty of Science, Chulalongkorn University, 254 Phayathai Road, Pathumwan, Bangkok 10330, Thailand
³⁶ National Astronomical Research Institute of Thailand (Public Organization), Donkaew, Maerim, Chiangmai 50180, Thailand
³⁷ Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo, Kashiwa, Chiba 277-8583, Japan

Received: 30 April 2020
Accepted: 31 August 2020

Abstract

We investigate the properties of a sample of 35 galaxies, detected with the Atacama Large Millimeter/Submillimeter Array (ALMA) at 1.1 mm in the GOODS-ALMA field (area of 69 arcmin², resolution = 0.60″, rms ≃ 0.18 mJy beam⁻¹). Using the ultraviolet-to-radio deep multiwavelength coverage of the GOODS–South field, we fit the spectral energy distributions of these galaxies to derive their key physical properties. The galaxies detected by ALMA are among the most massive at z = 2−4 (M_⋆, med = 8.5 × 10¹⁰ M_⊙) and they are either starburst or located in the upper part of the galaxy star-forming main sequence. A significant portion of our galaxy population (∼40%), located at z ∼ 2.5 − 3, exhibits abnormally low gas fractions. The sizes of these galaxies, measured with ALMA, are compatible with the trend between the rest-frame 5000 Å size and stellar mass observed for z ∼ 2 elliptical galaxies, suggesting that they are building compact bulges. We show that there is a strong link between star formation surface density (at 1.1 mm) and gas depletion time: The more compact a galaxy’s star-forming region is, the shorter its lifetime will be (without gas replenishment). The identified compact sources associated with relatively short depletion timescales (∼100 Myr) are the ideal candidates to be the progenitors of compact elliptical galaxies at z ∼ 2.