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The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Nature of the Faintest Dusty Star-forming Galaxies

Aravena, Manuel; Boogaard, Leindert; Gónzalez-López, Jorge; Decarli, Roberto; Walter, Fabian; Carilli, Chris L.; Smail, Ian; Weiss, Axel; Assef, Roberto J.; Bauer, Franz Erik; Bouwens, Rychard J.; Cortes, Paulo C.; Cox, Pierre; da Cunha, Elisabete; Daddi, Emanuele; Díaz-Santos, Tanio; Inami, Hanae; Ivison, Rob; Novak, Mladen; Popping, Gergö; Riechers, Dominik; van der Werf, Paul; Wagg, Jeff

The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Nature of the Faintest Dusty Star-forming Galaxies Thumbnail


Authors

Manuel Aravena

Leindert Boogaard

Jorge Gónzalez-López

Roberto Decarli

Fabian Walter

Chris L. Carilli

Axel Weiss

Roberto J. Assef

Franz Erik Bauer

Rychard J. Bouwens

Paulo C. Cortes

Pierre Cox

Elisabete da Cunha

Emanuele Daddi

Tanio Díaz-Santos

Hanae Inami

Rob Ivison

Mladen Novak

Gergö Popping

Dominik Riechers

Paul van der Werf

Jeff Wagg



Abstract

We present a characterization of the physical properties of a sample of 35 securely detected, dusty galaxies in the deep ALMA 1.2 mm image obtained as part of the ALMA Spectroscopic Survey in the Hubble Ultra Deep Field (ASPECS) Large Program. This sample is complemented by 26 additional sources identified via an optical/ infrared source positional prior. Using their well-characterized spectral energy distributions, we derive median stellar masses and star formation rates (SFR) of 4.8 10 ´ 10 M☉ and 30 M☉ yr−1 , respectively, and interquartile ranges of (2.4–11.7) × 1010 M☉ and 20–50 M☉ yr−1 . We derive a median spectroscopic redshift of 1.8 with an interquartile range 1.1–2.6, significantly lower than submillimeter galaxies detected in shallower, wide-field surveys. We find that 59% ± 13%, 6% ± 4%, and 34% ± 9% of our sources are within, above, and below±0.4 dex from the SFR–stellar-mass relation or main sequence (MS), respectively. The ASPECS galaxies closely follow the SFR–molecular gas mass relation and other previously established scaling relations, confirming a factor of five increase of the gas-to-stellar-mass ratio from z = 0.5 to 2.5 and a mild evolution of the gas depletion timescales with a typical value of 0.7 Gyr at z = 1–3. ASPECS galaxies located significantly below the MS, a poorly exploited parameter space, have low gas-to-stellar-mass ratios of ∼0.1–0.2 and long depletion timescales >1 Gyr. Galaxies along the MS dominate the cosmic density of molecular gas at all redshifts. Systems above the MS have an increasing contribution to the total gas reservoirs from z < 1 to z = 2.5, while the opposite is found for galaxies below the MS.

Citation

Aravena, M., Boogaard, L., Gónzalez-López, J., Decarli, R., Walter, F., Carilli, C. L., …Wagg, J. (2020). The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: The Nature of the Faintest Dusty Star-forming Galaxies. Astrophysical Journal, 901(1), Article 79. https://doi.org/10.3847/1538-4357/ab99a2

Journal Article Type Article
Acceptance Date Jun 3, 2020
Online Publication Date Sep 24, 2020
Publication Date 2020-09
Deposit Date Oct 27, 2020
Publicly Available Date Oct 27, 2020
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 901
Issue 1
Article Number 79
DOI https://doi.org/10.3847/1538-4357/ab99a2

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Copyright Statement
© 2020. The American Astronomical Society. All rights reserved.





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