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The CO Luminosity Density at High-z (COLDz) Survey: A Sensitive, Large-area Blind Search for Low-J CO Emission from Cold Gas in the Early Universe with the Karl G. Jansky Very Large Array

Pavesi, Riccardo; Sharon, Chelsea E.; Riechers, Dominik A.; Hodge, Jacqueline A.; Decarli, Roberto; Walter, Fabian; Carilli, Chris L.; Daddi, Emanuele; Smail, Ian; Dickinson, Mark; Ivison, Rob J.; Sargent, Mark; Cunha, Elisabete da; Aravena, Manuel; Darling, Jeremy; Smolčić, Vernesa; Scoville, Nicholas Z.; Capak, Peter L.; Wagg, Jeff

The CO Luminosity Density at High-z (COLDz) Survey: A Sensitive, Large-area Blind Search for Low-J CO Emission from Cold Gas in the Early Universe with the Karl G. Jansky Very Large Array Thumbnail


Authors

Riccardo Pavesi

Chelsea E. Sharon

Dominik A. Riechers

Jacqueline A. Hodge

Roberto Decarli

Fabian Walter

Chris L. Carilli

Emanuele Daddi

Mark Dickinson

Rob J. Ivison

Mark Sargent

Elisabete da Cunha

Manuel Aravena

Jeremy Darling

Vernesa Smolčić

Nicholas Z. Scoville

Peter L. Capak

Jeff Wagg



Abstract

We describe the CO Luminosity Density at High-z (COLDz) survey, the first spectral line deep field targeting CO(1–0) emission from galaxies at z = 1.95–2.85 and CO(2–1) at z = 4.91–6.70. The main goal of COLDz is to constrain the cosmic density of molecular gas at the peak epoch of cosmic star formation. By targeting both a wide (~51 arcmin2) and a deep (~9 arcmin2) area, the survey is designed to robustly constrain the bright end and the characteristic luminosity of the CO(1–0) luminosity function. An extensive analysis of the reliability of our line candidates and new techniques provide detailed completeness and statistical corrections as necessary to determine the best constraints to date on the CO luminosity function. Our blind search for CO(1–0) uniformly selects starbursts and massive main-sequence galaxies based on their cold molecular gas masses. Our search also detects CO(2–1) line emission from optically dark, dusty star-forming galaxies at z > 5. We find a range of spatial sizes for the CO-traced gas reservoirs up to ~40 kpc, suggesting that spatially extended cold molecular gas reservoirs may be common in massive, gas-rich galaxies at z ~ 2. Through CO line stacking, we constrain the gas mass fraction in previously known typical star-forming galaxies at z = 2–3. The stacked CO detection suggests lower molecular gas mass fractions than expected for massive main-sequence galaxies by a factor of ~3–6. We find total CO line brightness at ~34 GHz of 0.45 ± 0.2 μK, which constrains future line intensity mapping and CMB experiments.

Citation

Pavesi, R., Sharon, C. E., Riechers, D. A., Hodge, J. A., Decarli, R., Walter, F., …Wagg, J. (2018). The CO Luminosity Density at High-z (COLDz) Survey: A Sensitive, Large-area Blind Search for Low-J CO Emission from Cold Gas in the Early Universe with the Karl G. Jansky Very Large Array. Astrophysical Journal, 864(1), Article 49. https://doi.org/10.3847/1538-4357/aacb79

Journal Article Type Article
Acceptance Date Jun 6, 2018
Online Publication Date Aug 29, 2018
Publication Date Aug 29, 2018
Deposit Date Sep 13, 2018
Publicly Available Date Sep 13, 2018
Journal Astrophysical Journal
Print ISSN 0004-637X
Publisher American Astronomical Society
Peer Reviewed Peer Reviewed
Volume 864
Issue 1
Article Number 49
DOI https://doi.org/10.3847/1538-4357/aacb79

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Copyright Statement
© 2018. The American Astronomical Society. All rights reserved.





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