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ALMA Deep Field in SSA22: A Concentration of Dusty Starbursts in a z = 3.09 Protocluster Core

Umehata, H.; Tamura, Y.; Kohno, K.; Ivison, R.J.; Alexander, D.M.; Geach, J.E.; Hatsukade, B.; Hughes, D.H.; Ikarashi, S.; Kato, Y.; Izumi, T.; Kawabe, R.; Kubo, M.; Lee, M.; Lehmer, B.; Makiya, R.; Matsuda, Y.; Nakanishi, K.; Saito, T.; Smail, I.; Yamada, T.; Yamaguchi, Y.; Yun, M.

ALMA Deep Field in SSA22: A Concentration of Dusty Starbursts in a z = 3.09 Protocluster Core Thumbnail


H. Umehata

Y. Tamura

K. Kohno

R.J. Ivison

J.E. Geach

B. Hatsukade

D.H. Hughes

S. Ikarashi

Y. Kato

T. Izumi

R. Kawabe

M. Kubo

M. Lee

B. Lehmer

R. Makiya

Y. Matsuda

K. Nakanishi

T. Saito

T. Yamada

Y. Yamaguchi

M. Yun


We report the results of 1farcm5 × 3' mapping at 1.1 mm with the Atacama Large Millimeter/submillimeter Array toward the central region of the z = 3.09 SSA22 protocluster. By combining our source catalog with archival spectroscopic redshifts, we find that eight submillimeter galaxies (SMGs) with flux densities, S1.1 mm = 0.7–6.4 mJy (LIR ~ 1012.1–1013.1 L⊙) are at z = 3.08–3.10. Not only are these SMGs members of the protocluster, but they in fact reside within the node at the junction of the 50 Mpc scale filamentary three-dimensional structure traced by Lyα emitters in this field. The eight SMGs account for a star formation rate density (SFRD) ~10 M⊙ yr−1 Mpc−3 in the node, which is two orders of magnitudes higher than the global SFRD at this redshift. We find that four of the eight SMGs host an X-ray-luminous active galactic nucleus. Our results suggest that the vigorous star formation activity and the growth of supermassive black holes (SMBHs) occurred simultaneously in the densest regions at z ~ 3, which may correspond to the most active historical phase of the massive galaxy population found in the core of the clusters in the present universe. Two SMGs are associated with Lyα blobs, implying that the two populations coexist in high-density environments for a few cases.


Umehata, H., Tamura, Y., Kohno, K., Ivison, R., Alexander, D., Geach, J., …Yun, M. (2015). ALMA Deep Field in SSA22: A Concentration of Dusty Starbursts in a z = 3.09 Protocluster Core. Astrophysical Journal Letters, 815, Article L8.

Journal Article Type Article
Acceptance Date Oct 29, 2015
Online Publication Date Dec 4, 2015
Publication Date Dec 10, 2015
Deposit Date Feb 16, 2016
Publicly Available Date Feb 19, 2016
Journal Astrophysical Journal Letters
Print ISSN 2041-8205
Electronic ISSN 2041-8213
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 815
Article Number L8
Public URL


Published Journal Article (1.3 Mb)

Copyright Statement
© 2015. The American Astronomical Society. All rights reserved.

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