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FIR-luminous [C II] Emitters in the ALMA-SCUBA-2 COSMOS Survey (AS2COSMOS): The Nature of Submillimeter Galaxies in a 10 Comoving Megaparsec-scale Structure at z \ensuremath\sim 4.6

Mitsuhashi, I.; Matsuda, Y.; Smail, Ian; Hayatsu, N.H.; Simpson, J.M.; Swinbank, A.M.; Umehata, H.; Dudzeviciute, U.; Birkin, J.E.; Ikarashi, S.; Chen, Chian-Chou; Tadaki, K.; Yajima, H.; Harikane, Y.; Inami, H.; Chapman, S.C.; Hatsukade, B.; Iono, D.; Bunker, A.; Ao, Y.; Saito, T.; Ueda, J.; Sakamoto, S.

FIR-luminous [C II] Emitters in the ALMA-SCUBA-2 COSMOS Survey (AS2COSMOS): The Nature of Submillimeter Galaxies in a 10 Comoving Megaparsec-scale Structure at z \ensuremath\sim 4.6 Thumbnail


Authors

I. Mitsuhashi

Y. Matsuda

N.H. Hayatsu

J.M. Simpson

H. Umehata

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Jack Birkin jack.birkin@durham.ac.uk
PGR Student Doctor of Philosophy

S. Ikarashi

Chian-Chou Chen

K. Tadaki

H. Yajima

Y. Harikane

H. Inami

S.C. Chapman

B. Hatsukade

D. Iono

A. Bunker

Y. Ao

T. Saito

J. Ueda

S. Sakamoto



Abstract

We report the discovery of a 10 comoving megaparsec (cMpc)-scale structure traced by massive submillimeter galaxies (SMGs) at z ∼ 4.6. These galaxies are selected from an emission line search of ALMA Band 7 observations targeting 184 luminous submillimeter sources (S850μm ≥ 6.2 mJy) across 1.6 degrees2 in the COSMOS field. We identify four [C ii] emitting SMGs and two probable [C ii] emitting SMG candidates at z = 4.60–4.64 with velocity-integrated signal-to-noise ratio of S/N > 8. Four of the six emitters are near-infrared blank SMGs. After excluding one SMG whose emission line is falling at the edge of the spectral window, all galaxies show clear velocity gradients along the major axes that are consistent with rotating gas disks. The estimated rotation velocities of the disks are 330–550 km s−1 and the inferred host dark-matter halo masses are ∼2–8 × 1012 M⊙. From their estimated halo masses and [C ii] luminosity function, we suggest that these galaxies have a high (50%–100%) duty cycle and high (∼0.1) baryon conversion efficiency (SFR relative to baryon accretion rate), and that they contribute ≃2% to the total star formation rate density at z = 4.6. These SMGs are concentrated within just 0.3% of the full survey volume, suggesting they are strongly clustered. The extent of this structure and the individual halo masses suggest that these SMGs will likely evolve into members of a ∼1015 M⊙ cluster at z = 0. This survey reveals a synchronized dusty starburst in massive halos at z > 4, which could be driven by mergers or fed by smooth gas accretion.

Journal Article Type Article
Acceptance Date Nov 18, 2020
Online Publication Date Feb 5, 2021
Publication Date 2021-02
Deposit Date May 5, 2021
Publicly Available Date Feb 5, 2022
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 907
Issue 2
Article Number 122
DOI https://doi.org/10.3847/1538-4357/abcc72
Public URL https://durham-repository.worktribe.com/output/1248664

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