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Journal Articles The Astrophysical Journal Year : 2016

ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description

Fabian Walter
Roberto Decarli
Manuel Aravena
Chris Carilli
Rychard Bouwens
Elisabete da Cunha
Emanuele Daddi
R. J. Ivison
  • Function : Author
Dominik Riechers
Ian Smail
Mark Swinbank
  • Function : Author
Axel Weiss
Timo Anguita
  • Function : Author
Roberto Assef
Roland Bacon
  • Function : Author
Franz Bauer
Eric F. Bell
  • Function : Author
Frank Bertoldi
Scott Chapman
  • Function : Author
Luis Colina
  • Function : Author
Paulo C. Cortes
  • Function : Author
Pierre Cox
  • Function : Author
Mark Dickinson
David Elbaz
  • Function : Author
Jorge Gónzalez-López
Edo Ibar
  • Function : Author
Hanae Inami
Leopoldo Infante
  • Function : Author
Jacqueline Hodge
Alex Karim
  • Function : Author
Benjamin Magnelli
Roberto Neri
Pascal Oesch
Kazuaki Ota
  • Function : Author
Gergö Popping
Hans-Walter Rix
Mark Sargent
Kartik Sheth
Arjen van Der Wel
  • Function : Author
Paul van Der Werf
Jeff Wagg
  • Function : Author


We present the rationale for and the observational description of ASPECS: the ALMA SPECtroscopic Survey in the Hubble Ultra-Deep Field (UDF), the cosmological deep field that has the deepest multi-wavelength data available. Our overarching goal is to obtain an unbiased census of molecular gas and dust continuum emission in high-redshift (z > 0.5) galaxies. The ∼1‧ region covered within the UDF was chosen to overlap with the deepest available imaging from the Hubble Space Telescope. Our ALMA observations consist of full frequency scans in band 3 (84-115 GHz) and band 6 (212-272 GHz) at approximately uniform line sensitivity ({L}{CO}\prime ∼ 2 × 109 K km s-1 pc2), and continuum noise levels of 3.8 μJy beam-1 and 12.7 μJy beam-1, respectively. The molecular surveys cover the different rotational transitions of the CO molecule, leading to essentially full redshift coverage. The [C II] emission line is also covered at redshifts 6.0 z 8.0. We present a customized algorithm to identify line candidates in the molecular line scans and quantify our ability to recover artificial sources from our data. Based on whether multiple CO lines are detected, and whether optical spectroscopic redshifts as well as optical counterparts exist, we constrain the most likely line identification. We report 10 (11) CO line candidates in the 3 mm (1 mm) band, and our statistical analysis shows that <4 of these (in each band) are likely spurious. Less than one-third of the total CO flux in the low-J CO line candidates are from sources that are not associated with an optical/NIR counterpart. We also present continuum maps of both the band 3 and band 6 observations. The data presented here form the basis of a number of dedicated studies that are presented in subsequent papers.

Dates and versions

insu-03667691 , version 1 (13-05-2022)



Fabian Walter, Roberto Decarli, Manuel Aravena, Chris Carilli, Rychard Bouwens, et al.. ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Survey Description. The Astrophysical Journal, 2016, 833, ⟨10.3847/1538-4357/833/1/67⟩. ⟨insu-03667691⟩
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