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COLDz: A High Space Density of Massive Dusty Starburst Galaxies ∼1 Billion Years after the Big Bang

Riechers, Dominik A. and Hodge, Jacqueline A. and Pavesi, Riccardo and Daddi, Emanuele and Decarli, Roberto and Ivison, Rob J. and Sharon, Chelsea E. and Smail, Ian and Walter, Fabian and Aravena, Manuel and Capak, Peter L. and Carilli, Christopher L. and Cox, Pierre and da Cunha, Elisabete and Dannerbauer, Helmut and Dickinson, Mark and Neri, Roberto and Wagg, Jeff (2020) COLDz: A High Space Density of Massive Dusty Starburst Galaxies ∼1 Billion Years after the Big Bang. Astrophysical Journal, 895 (2). Art. No. 81. ISSN 1538-4357.

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We report the detection of CO(J = 2 → 1) emission from three massive dusty starburst galaxies at z > 5 through molecular line scans in the NSF's Karl G. Jansky Very Large Array (VLA) CO Luminosity Density at High Redshift (COLDz) survey. Redshifts for two of the sources, HDF 850.1 (z = 5.183) and AzTEC-3 (z = 5.298), were previously known. We revise a previous redshift estimate for the third source GN10 (z = 5.303), which we have independently confirmed through detections of CO J = 1 → 0, 5 → 4, 6 → 5, and [C II] 158 μm emission with the VLA and the NOrthern Extended Milllimeter Array. We find that two currently independently confirmed CO sources in COLDz are "optically dark", and that three of them are dust-obscured galaxies at z > 5. Given our survey area of ~60 arcmin², our results appear to imply a ~6–55 times higher space density of such distant dusty systems within the first billion years after the Big Bang than previously thought. At least two of these z > 5 galaxies show star formation rate surface densities consistent with so-called "maximum" starbursts, but we find significant differences in CO excitation between them. This result may suggest that different fractions of the massive gas reservoirs are located in the dense, star-forming nuclear regions—consistent with the more extended sizes of the [C II] emission compared to the dust continuum and higher [C II]-to-far-infrared luminosity ratios in those galaxies with lower gas excitation. We thus find substantial variations in the conditions for star formation between z > 5 dusty starbursts, which typically have dust temperatures that are ~57% ± 25% warmer than starbursts at z = 2–3 due to their enhanced star formation activity.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Riechers, Dominik A.0000-0001-9585-1462
Hodge, Jacqueline A.0000-0001-6586-8845
Pavesi, Riccardo0000-0002-2263-646X
Daddi, Emanuele0000-0002-3331-9590
Decarli, Roberto0000-0002-2662-8803
Ivison, Rob J.0000-0001-5118-1313
Sharon, Chelsea E.0000-0002-6250-5608
Smail, Ian0000-0003-3037-257X
Walter, Fabian0000-0003-4793-7880
Aravena, Manuel0000-0002-6290-3198
Capak, Peter L.0000-0003-3578-6843
Carilli, Christopher L.0000-0001-6647-3861
Cox, Pierre0000-0003-2027-8221
da Cunha, Elisabete0000-0001-9759-4797
Dannerbauer, Helmut0000-0001-7147-3575
Dickinson, Mark0000-0001-5414-5131
Neri, Roberto0000-0002-7176-4046
Additional Information:© 2020 The American Astronomical Society. Received 2020 January 20; revised 2020 April 17; accepted 2020 April 21; published 2020 May 28. We thank the anonymous referee for a careful reading of the manuscript and helpful comments that led to improvements in the structure and content of this work. We also thank Christian Henkel for the original version of the LVG code, Daizhong Liu for sharing results on the de-blended photometry of GN10 in an early stage of the analysis and the source data used in Figure 11, Zhi-Yu Zhang for enlightening discussions, and Ugne Dudzeviciute for help with the AS2COSMOS number density calculations. D.R. and R.P. acknowledge support from the National Science Foundation under grant Nos. AST-1614213 and AST-1910107 to Cornell University. D.R. also acknowledges support from the Alexander von Humboldt Foundation through a Humboldt Research Fellowship for Experienced Researchers. J.H. acknowledges support of the VIDI research program with project No. 639.042.611, which is (partly) financed by the Netherlands Organization for Scientific Research (NWO). I.R.S. acknowledges support from STFC (ST/P000541/1). H.D. acknowledges financial support from the Spanish Ministry of Science, Innovation and Universities (MICIU) under the 2014 Ramón y Cajal program RYC-2014-15686 and AYA2017-84061-P, the latter one being co-financed by FEDER (European Regional Development Funds). The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Facilities: VLA - Very Large Array, NOEMA. -
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Alexander von Humboldt FoundationUNSPECIFIED
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)639.042.611
Science and Technology Facilities Council (STFC)ST/P000541/1
Ministerio de Economía, Industria y Competitividad (MINECO)RYC-2014-15686
Ministerio de Ciencia, Innovación y Universidades (MICIU)AYA2017-84061-P
European Regional Development Funds (ERDF)UNSPECIFIED
Subject Keywords:Active galaxies ; Galaxy evolution ; Starburst galaxies ; High-redshift galaxies ; Infrared excess galaxies ; Observational cosmology ; Interstellar line emission ; Submillimeter astronomy ; Millimeter astronomy
Issue or Number:2
Classification Code:Unified Astronomy Thesaurus concepts: Active galaxies (17); Galaxy evolution (594); Starburst galaxies (1570); High-redshift galaxies (734); Infrared excess galaxies (789); Observational cosmology (1146); Interstellar line emission (844)
Record Number:CaltechAUTHORS:20200528-130932597
Persistent URL:
Official Citation:Dominik A. Riechers et al 2020 ApJ 895 81
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103520
Deposited By: Tony Diaz
Deposited On:28 May 2020 20:35
Last Modified:28 May 2020 20:35

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