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The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2 mm Extragalactic Background, and Properties of the Faintest Dusty Star-forming Galaxies

Aravena, M.; Decarli, R.; Walter, F.; Da Cunha, E.; Bauer, F.E.; Carilli, C.L.; Daddi, E.; Elbaz, D.; Ivison, R.J.; Riechers, D.A.; Smail, I.; Swinbank, A.M.; Weiss, A.; Anguita, T.; Assef, R.J.; Bell, E.; Bertoldi, F.; Bacon, R.; Bouwens, R.; Cortes, P.; Cox, P.; Gónzalez-López, J.; Hodge, J.; Ibar, E.; Inami, H.; Infante, L.; Karim, A.; Le Le Fèvre, O.; Magnelli, B.; Ota, K.; Popping, G.; Sheth, K.; van der Werf, P.; Wagg, J.

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2 mm Extragalactic Background, and Properties of the Faintest Dusty Star-forming Galaxies Thumbnail


Authors

M. Aravena

R. Decarli

F. Walter

E. Da Cunha

F.E. Bauer

C.L. Carilli

E. Daddi

D. Elbaz

R.J. Ivison

D.A. Riechers

A. Weiss

T. Anguita

R.J. Assef

E. Bell

F. Bertoldi

R. Bacon

R. Bouwens

P. Cortes

P. Cox

J. Gónzalez-López

J. Hodge

E. Ibar

H. Inami

L. Infante

A. Karim

O. Le Le Fèvre

B. Magnelli

K. Ota

G. Popping

K. Sheth

P. van der Werf

J. Wagg



Abstract

We present an analysis of a deep (1σ = 13 μJy) cosmological 1.2 mm continuum map based on ASPECS, the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field. In the 1 arcmin2 covered by ASPECS we detect nine sources at \gt 3.5σ significance at 1.2 mm. Our ALMA-selected sample has a median redshift of z=1.6+/- 0.4, with only one galaxy detected at z > 2 within the survey area. This value is significantly lower than that found in millimeter samples selected at a higher flux density cutoff and similar frequencies. Most galaxies have specific star formation rates (SFRs) similar to that of main-sequence galaxies at the same epoch, and we find median values of stellar mass and SFRs of 4.0× {10}10 {M}⊙ and ˜ 40 {M}⊙ yr-1, respectively. Using the dust emission as a tracer for the interstellar medium (ISM) mass, we derive depletion times that are typically longer than 300 Myr, and we find molecular gas fractions ranging from ˜0.1 to 1.0. As noted by previous studies, these values are lower than those using CO-based ISM estimates by a factor of ˜2. The 1 mm number counts (corrected for fidelity and completeness) are in agreement with previous studies that were typically restricted to brighter sources. With our individual detections only, we recover 55% ± 4% of the extragalactic background light (EBL) at 1.2 mm measured by the Planck satellite, and we recover 80% ± 7% of this EBL if we include the bright end of the number counts and additional detections from stacking. The stacked contribution is dominated by galaxies at z˜ 1{--}2, with stellar masses of (1-3) × 1010 M {}⊙ . For the first time, we are able to characterize the population of galaxies that dominate the EBL at 1.2 mm.

Citation

Aravena, M., Decarli, R., Walter, F., Da Cunha, E., Bauer, F., Carilli, C., …Wagg, J. (2016). The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Continuum Number Counts, Resolved 1.2 mm Extragalactic Background, and Properties of the Faintest Dusty Star-forming Galaxies. Astrophysical Journal, 833(1), Article 68. https://doi.org/10.3847/1538-4357/833/1/68

Journal Article Type Article
Acceptance Date Nov 6, 2016
Online Publication Date Dec 8, 2016
Publication Date Dec 8, 2016
Deposit Date Feb 22, 2017
Publicly Available Date Mar 9, 2017
Journal Astrophysical Journal
Print ISSN 0004-637X
Electronic ISSN 1538-4357
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 833
Issue 1
Article Number 68
DOI https://doi.org/10.3847/1538-4357/833/1/68
Related Public URLs https://arxiv.org/abs/1607.06769

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Copyright Statement
© 2016. The American Astronomical Society. All rights reserved.





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