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COLDz: Shape of the CO Luminosity Function at High Redshift and the Cold Gas History of the Universe

Riechers, Dominik A. and Pavesi, Riccardo and Sharon, Chelsea E. and Hodge, Jacqueline A. and Decarli, Roberto and Walter, Fabian and Carilli, Christopher L. and Aravena, Manuel and da Cunha, Elisabete and Daddi, Emanuele and Dickinson, Mark and Smail, Ian and Capak, Peter L. and Ivison, Rob J. and Sargent, Mark and Scoville, Nicholas Z. and Wagg, Jeff (2019) COLDz: Shape of the CO Luminosity Function at High Redshift and the Cold Gas History of the Universe. Astrophysical Journal, 872 (1). Art. No. 7. ISSN 1538-4357. doi:10.3847/1538-4357/aafc27.

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We report the first detailed measurement of the shape of the CO luminosity function at high redshift, based on >320 hr of the NSF's Karl G. Jansky Very Large Array (VLA) observations over an area of ~60 arcmin^2 taken as part of the CO Luminosity Density at High Redshift (COLDz) survey. COLDz "blindly" selects galaxies based on their cold gas content through CO(J = 1 → 0) emission at z ~ 2–3 and CO(J = 2 → 1) at z ~ 5–7 down to a CO luminosity limit of log(L’_(CO)/K km s^(−1) pc^2) ≃ 9.5. We find that the characteristic luminosity and bright end of the CO luminosity function are substantially higher than predicted by semi-analytical models, but consistent with empirical estimates based on the infrared luminosity function at z ~ 2. We also present the currently most reliable measurement of the cosmic density of cold gas in galaxies at early epochs, i.e., the cold gas history of the universe, as determined over a large cosmic volume of ~375,000 Mpc3. Our measurements are in agreement with an increase of the cold gas density from z ~ 0 to z ~ 2–3, followed by a possible decline toward z ~ 5–7. These findings are consistent with recent surveys based on higher-J CO line measurements, upon which COLDz improves in terms of statistical uncertainties by probing ~50–100 times larger areas and in the reliability of total gas mass estimates by probing the low-J CO lines accessible to the VLA. Our results thus appear to suggest that the cosmic star formation rate density follows an increased cold molecular gas content in galaxies toward its peak about 10 billion years ago, and that its decline toward the earliest epochs is likely related to a lower overall amount of cold molecular gas (as traced by CO) bound in galaxies toward the first billion years after the Big Bang.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Riechers, Dominik A.0000-0001-9585-1462
Pavesi, Riccardo0000-0002-2263-646X
Sharon, Chelsea E.0000-0002-6250-5608
Hodge, Jacqueline A.0000-0001-6586-8845
Decarli, Roberto0000-0002-2662-8803
Walter, Fabian0000-0003-4793-7880
Carilli, Christopher L.0000-0001-6647-3861
Aravena, Manuel0000-0002-6290-3198
da Cunha, Elisabete0000-0001-9759-4797
Daddi, Emanuele0000-0002-3331-9590
Dickinson, Mark0000-0001-5414-5131
Smail, Ian0000-0003-3037-257X
Capak, Peter L.0000-0003-3578-6843
Ivison, Rob J.0000-0001-5118-1313
Sargent, Mark0000-0003-1033-9684
Scoville, Nicholas Z.0000-0002-0438-3323
Additional Information:© 2019 The American Astronomical Society. Received 2018 August 10; revised 2018 November 27; accepted 2019 January 4; published 2019 February 6. The authors thank Amélie Saintonge for sharing her updated Schechter fits to the local CO luminosity function prior to publication, Rychard Bouwens for sharing the data necessary to create Figure 5, and Gergö Popping for helpful input on the comparison of our results to models, and for providing some new and updated model results. We also thank the anonymous referee for a helpful report. D.R. and R.P. acknowledge support from the National Science Foundation under grant number AST-1614213 to Cornell University. J.A.H. acknowledges support of the VIDI research program with project number 639.042.611, which is (partly) financed by the Netherlands Organisation for Scientific Research (NWO). I.R.S. acknowledges support from the ERC Advanced Grant DUSTYGAL (321334), STFC (ST/P000541/1), and a Royal Society/Wolfson Merit Award. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Facility: VLA. -
Group:COSMOS, Infrared Processing and Analysis Center (IPAC), Astronomy Department
Funding AgencyGrant Number
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)639.042.611
European Research Council (ERC)321334
Science and Technology Facilities Council (STFC)ST/P000541/1
Subject Keywords:cosmology: observations – galaxies: active – galaxies: formation – galaxies: high-redshift – galaxies: starburst – radio lines: galaxies
Issue or Number:1
Record Number:CaltechAUTHORS:20180904-152724469
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Official Citation:Dominik A. Riechers et al 2019 ApJ 872 7
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89367
Deposited By: Tony Diaz
Deposited On:04 Sep 2018 23:05
Last Modified:16 Nov 2021 00:34

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