GOODS-ALMA: Optically dark ALMA galaxies shed light on a cluster in formation at z = 3.5

Zhou, L.; Elbaz, D.; Franco, M.; Magnelli, B.; Schreiber, C.; Wang, T.; Ciesla, L.; Daddi, E.; Dickinson, M.; Nagar, N.; Magdis, G.; Alexander, D.M.; Béthermin, M.; Demarco, R.; Mullaney, J.; Bournaud, F.; Ferguson, H.; Finkelstein, S.L.; Giavalisco, M.; Inami, H.; Iono, D.; Juneau, S.; Lagache, G.; Messias, H.; Motohara, K.; Okumura, K.; Pannella, M.; Papovich, C.; Pope, A.; Rujopakarn, W.; Shi, Y.; Shu, X.; Silverman, J.

doi:10.1051/0004-6361/202038059

GOODS-ALMA: Optically dark ALMA galaxies shed light on a cluster in formation at z = 3.5

Zhou, L.; Elbaz, D.; Franco, M.; Magnelli, B.; Schreiber, C.; Wang, T.; Ciesla, L.; Daddi, E.; Dickinson, M.; Nagar, N.; Magdis, G.; Alexander, D.M.; Béthermin, M.; Demarco, R.; Mullaney, J.; Bournaud, F.; Ferguson, H.; Finkelstein, S.L.; Giavalisco, M.; Inami, H.; Iono, D.; Juneau, S.; Lagache, G.; Messias, H.; Motohara, K.; Okumura, K.; Pannella, M.; Papovich, C.; Pope, A.; Rujopakarn, W.; Shi, Y.; Shu, X.; Silverman, J.

Authors

L. Zhou

D. Elbaz

M. Franco

B. Magnelli

C. Schreiber

T. Wang

L. Ciesla

E. Daddi

M. Dickinson

N. Nagar

G. Magdis

Professor David Alexander d.m.alexander@durham.ac.uk
Professor

M. Béthermin

R. Demarco

J. Mullaney

F. Bournaud

H. Ferguson

S.L. Finkelstein

M. Giavalisco

H. Inami

D. Iono

S. Juneau

G. Lagache

H. Messias

K. Motohara

K. Okumura

M. Pannella

C. Papovich

A. Pope

W. Rujopakarn

Y. Shi

X. Shu

J. Silverman

Abstract

Thanks to its outstanding angular resolution, the Atacama Large Millimeter/submillimeter Array (ALMA) has recently unambiguously identified a population of optically dark galaxies with redshifts greater than z = 3, which play an important role in the cosmic star formation in massive galaxies. In this paper we study the properties of the six optically dark galaxies detected in the 69 arcmin2 GOODS-ALMA 1.1 mm continuum survey. While none of them are listed in the deepest H-band based CANDELS catalog in the GOODS-South field down to H = 28.16 AB, we were able to de-blend two of them from their bright neighbor and measure an H-band flux for them. We present the spectroscopic scan follow-up of five of the six sources with ALMA band 4. All are detected in the 2 mm continuum with signal-to-noise ratios higher than eight. One emission line is detected in AGS4 (νobs = 151.44 GHz with an S/N = 8.58) and AGS17 (νobs = 154.78 GHz with an S/N = 10.23), which we interpret in both cases as being due to the CO(6–5) line at zspecAGS4 = 3.556 and zspecAGS17 = 3.467, respectively. These redshifts match both the probability distribution of the photometric redshifts derived from the UV to near-infrared spectral energy distributions (SEDs) and the far-infrared SEDs for typical dust temperatures of galaxies at these redshifts. We present evidence that nearly 70% (4/6 of galaxies) of the optically dark galaxies belong to the same overdensity of galaxies at z ∼ 3.5. overdensity The most massive one, AGS24 (M⋆ = 1011.32−0.19+0.02 M⊙), is the most massive galaxy without an active galactic nucleus at z > 3 in the GOODS-ALMA field. It falls in the very center of the peak of the galaxy surface density, which suggests that the surrounding overdensity is a proto-cluster in the process of virialization and that AGS24 is the candidate progenitor of the future brightest cluster galaxy.

Citation

Zhou, L., Elbaz, D., Franco, M., Magnelli, B., Schreiber, C., Wang, T., …Silverman, J. (2020). GOODS-ALMA: Optically dark ALMA galaxies shed light on a cluster in formation at z = 3.5. Astronomy & Astrophysics, 642, Article A155. https://doi.org/10.1051/0004-6361/202038059

Journal Article Type	Article
Acceptance Date	Aug 7, 2020
Online Publication Date	Oct 13, 2020
Publication Date	2020-10
Deposit Date	Nov 5, 2020
Publicly Available Date	Nov 5, 2020
Journal	Astronomy and astrophysics.
Print ISSN	0004-6361
Electronic ISSN	1432-0746
Publisher	EDP Sciences
Peer Reviewed	Peer Reviewed
Volume	642
Article Number	A155
DOI	https://doi.org/10.1051/0004-6361/202038059

Files

Published Journal Article (3.6 Mb)
PDF

Copyright Statement
Zhou, L., Elbaz, D., Franco, M., Magnelli, B., Schreiber, C., Wang, T., Ciesla, L., Daddi, E., Dickinson, M., Nagar, N., Magdis, G., Alexander, D. M., Béthermin, M., Demarco, R., Mullaney, J., Bournaud, F., Ferguson, H., Finkelstein, S. L., Giavalisco, M., Inami, H., Iono, D., Juneau, S., Lagache, G., Messias, H., Motohara, K., Okumura, K., Pannella, M., Papovich, C., Pope, A., Rujopakarn, W., Shi, Y., Shu, X. & Silverman, J. (2020). GOODS-ALMA: Optically dark ALMA galaxies shed light on a cluster in formation at z = 3.5. Astronomy & Astrophysics 642: A155 reproduced with permission, © ESO.