Volume 633, January 2020
|Number of page(s)||14|
|Published online||15 January 2020|
The ALPINE-ALMA [C II] survey: Star-formation-driven outflows and circumgalactic enrichment in the early Universe
Observatoire de Genève, Universitè de Genève, 51 Ch. des Maillettes, 1290 Versoix, Switzerland
2 Cavendish Laboratory, University of Cambridge, 19 J. J. Thomson Ave., Cambridge CB3 0HE, UK
3 Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
4 Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France
5 Osservatorio di Astrofisica e Scienza dello Spazio – Istituto Nazionale di Astrofisica, Via Gobetti 93/3, 40129 Bologna, Italy
6 University of Bologna, Department of Physics and Astronomy (DIFA), Via Gobetti 93/2, 40129 Bologna, Italy
7 Institute for Cosmic Ray Research, The University of Tokyo, Kashiwa-no-ha, Kashiwa 277-8582, Japan
8 Department of Astronomy, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033, Japan
9 IPAC, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
10 University of Padova, Department of Physics and Astronomy, Vicolo Osservatorio 3, 35122 Padova, Italy
11 Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), The University of Tokyo, Kashiwa 277-8583, Japan
12 Caltech Optical Observatories, Cahill Center for Astronomy and Astrophysics, 1200 East California Boulevard, Pasadena, CA 91125, USA
13 Centro de Astronomia (CITEVA), Universidad de Antofagasta, Avenida Angamos 601, Antofagasta, Chile
14 Instituto de Fisica y Astronomia, Universidad de Valparaiso, Gran Bretana 1111, Playa Ancha, Valparaiso, Chile
15 Department of Physics and Astronomy, University of Massachusetts, Amherst, MA 01003, USA
16 Department of Physics, University of California, Davis, One Shields Ave., Davis, CA 95616, USA
17 Department of Astronomy, University of Florida, 211 Bryant Space Sciences Center, Gainesville, FL 32611, USA
18 Cosmic Dawn Center (DAWN), Denmark
19 Niels Bohr Institute, University of Copenhagen, Lyngbyvej 2, 2100 Copenhagen, Denmark
20 Leiden Observatory, Leiden University, PO Box 9500, 2300 RA Leiden, The Netherlands
Accepted: 15 November 2019
We study the efficiency of galactic feedback in the early Universe by stacking the [C II] 158 μm emission in a large sample of normal star-forming galaxies at 4 < z < 6 from the ALMA Large Program to INvestigate [C II] at Early times (ALPINE) survey. Searching for typical signatures of outflows in the high-velocity tails of the stacked [C II] profile, we observe (i) deviations from a single-component Gaussian model in the combined residuals and (ii) broad emission in the stacked [C II] spectrum, with velocities of |v|≲500 km s−1. The significance of these features increases when stacking the subset of galaxies with star formation rates (SFRs) higher than the median (SFRmed = 25 M⊙ yr−1), thus confirming their star-formation-driven nature. The estimated mass outflow rates are comparable to the SFRs, yielding mass-loading factors of the order of unity (similarly to local star-forming galaxies), suggesting that star-formation-driven feedback may play a lesser role in quenching galaxies at z > 4. From the stacking analysis of the datacubes, we find that the combined [C II] core emission (|v|< 200 km s−1) of the higher-SFR galaxies is extended on physical sizes of ∼30 kpc (diameter scale), well beyond the analogous [C II] core emission of lower-SFR galaxies and the stacked far-infrared continuum. The detection of such extended metal-enriched gas, likely tracing circumgalactic gas enriched by past outflows, corroborates previous similar studies, confirming that baryon cycle and gas exchanges with the circumgalactic medium are at work in normal star-forming galaxies already at early epochs.
Key words: galaxies: evolution / galaxies: formation / galaxies: high-redshift / galaxies: ISM / ISM: jets and outflows / galaxies: star formation
© ESO 2020
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