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 - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 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

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

#### 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 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.

#### Domains

Sciences of the Universe [physics]

### Dates and versions

insu-03667690 , version 1 (13-05-2022)

### Identifiers

• HAL Id : insu-03667690 , version 1
• ARXIV :
• BIBCODE :
• DOI :

### Cite

M. Aravena, R. Decarli, F. Walter, E. da Cunha, F. E. Bauer, et al.. 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. The Astrophysical Journal, 2016, 833, ⟨10.3847/1538-4357/833/1/68⟩. ⟨insu-03667690⟩

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