Witnessing the Birth of the Red Sequence: ALMA High-resolution Imaging of [C II] and Dust in Two Interacting Ultra-red Starbursts at z = 4.425

Author(s): I. Oteo, Rob J. Ivison, L Dunne, Ian R. Smail, A. Mark Swinbank, Helmut Dannerbauer
Abstract: Exploiting the sensitivity and spatial resolution of the Atacama Large Millimeter/submillimeter Array, we have studied the morphology and the physical scale of the interstellar medium—both gas and dust—in SGP 38326, an unlensed pair of interacting starbursts at z = 4.425. SGP 38326 is the most luminous star bursting system known at z > 4, with a total IR luminosity of L IR ~ 2.5 × 10¹³ L_⊙ and a star formation rate of ~ 4500 M_⊙ yr^-1. SGP 38326 also contains a molecular gas reservoir among the most massive yet found in the early universe, and it is the likely progenitor of a massive, red-and-dead elliptical galaxy at z ~ 3. Probing scales of ~0.″1 or ~800 pc we find that the smooth distribution of the continuum emission from cool dust grains contrasts with the more irregular morphology of the gas, as traced by the [C II] fine structure emission. The gas is also extended over larger physical scales than the dust. The velocity information provided by the resolved [C II] emission reveals that the dynamics of the two interacting components of SGP 38326 are each compatible with disk-like, ordered rotation, but also reveals an ISM which is turbulent and unstable. Our observations support a scenario where at least a subset of the most distant extreme starbursts are highly dissipative mergers of gas-rich galaxies.
Organisation(s): Department of Astrophysics
External organisation(s): The Royal Observatory, Edinburgh, Durham University
Journal: The Astrophysical Journal
Volume: 827
No. of pages: 11
ISSN: 0004-637X
DOI: https://doi.org/10.3847/0004-637X/827/1/34
Publication date: 08-2016
Peer reviewed: Yes
Austrian Fields of Science 2012: 103003 Astronomy, 103004 Astrophysics
Keywords
ASJC Scopus subject areas: Astronomy and Astrophysics, Space and Planetary Science
Portal url: https://ucrisportal.univie.ac.at/en/publications/bc4648d3-19f3-4cd7-a45f-4d960b141fa0

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