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Molecular gas in z ∼ 6 quasar host galaxies

Decarli, Roberto and Pensabene, Antonio and Venemans, Bram and Walter, Fabian and Bañados, Eduardo and Bertoldi, Frank and Carilli, Chris L. and Cox, Pierre and Fan, Xiaohui and Farina, Emanuele Paolo and Ferkinhoff, Carl and Groves, Brent A. and Li, Jianan and Mazzucchelli, Chiara and Neri, Roberto and Riechers, Dominik A. and Uzgil, Bade and Wang, Feige and Wang, Ran and Weiss, Axel and Winters, Jan Martin and Yang, Jinyi (2022) Molecular gas in z ∼ 6 quasar host galaxies. Astronomy and Astrophysics, 662 . Art. No. A60. ISSN 0004-6361. doi:10.1051/0004-6361/202142871.

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We investigate the molecular gas content of z ∼ 6 quasar host galaxies using the Institut de Radioastronomie Millimétrique Northern Extended Millimeter Array. We targeted the 3 mm dust continuum, and the line emission from CO(6–5), CO(7–6), and [C I]₂₋₁ in ten infrared–luminous quasars that have been previously studied in their 1 mm dust continuum and [C II] line emission. We detected CO(7–6) at various degrees of significance in all the targeted sources, thus doubling the number of such detections in z ∼ 6 quasars. The 3 mm to 1 mm flux density ratios are consistent with a modified black body spectrum with a dust temperature T_(dust) ∼ 47 K and an optical depth τ_ν = 0.2 at the [C II] frequency. Our study provides us with four independent ways to estimate the molecular gas mass, M_(H2,) in the targeted quasars. This allows us to set constraints on various parameters used in the derivation of molecular gas mass estimates, such as the mass per luminosity ratios α_(CO) and α_[CII], the gas-to-dust mass ratio δ_(g/d), and the carbon abundance [C]/H₂. Leveraging either on the dust, CO, [C I], or [C II] emission yields mass estimates of the entire sample in the range M_(H2) ∼ 10¹⁰–10¹¹ M_⊙. We compared the observed luminosities of dust, [C II], [C I], and CO(7–6) with predictions from photo-dissociation and X-ray dominated regions. We find that the former provide better model fits to our data, assuming that the bulk of the emission arises from dense (n_H > 10⁴ cm⁻³) clouds with a column density NH ∼ 10²³ cm⁻², exposed to a radiation field with an intensity of G₀ ∼ 10³ (in Habing units). Our analysis reiterates the presence of massive reservoirs of molecular gas fueling star formation and nuclear accretion in z ∼ 6 quasar host galaxies. It also highlights the power of combined 3 mm and 1 mm observations for quantitative studies of the dense gas content in massive galaxies at cosmic dawn.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Decarli, Roberto0000-0002-2662-8803
Pensabene, Antonio0000-0001-9815-4953
Venemans, Bram0000-0001-9024-8322
Walter, Fabian0000-0003-4793-7880
Bañados, Eduardo0000-0002-2931-7824
Bertoldi, Frank0000-0002-1707-1775
Carilli, Chris L.0000-0001-6647-3861
Cox, Pierre0000-0003-2027-8221
Fan, Xiaohui0000-0003-3310-0131
Farina, Emanuele Paolo0000-0002-6822-2254
Ferkinhoff, Carl0000-0001-6266-0213
Groves, Brent A.0000-0002-9768-0246
Mazzucchelli, Chiara0000-0002-5941-5214
Neri, Roberto0000-0002-7176-4046
Riechers, Dominik A.0000-0001-9585-1462
Uzgil, Bade0000-0001-8526-3464
Wang, Feige0000-0002-0210-7499
Wang, Ran0000-0003-4956-5742
Weiss, Axel0000-0003-4678-3939
Winters, Jan Martin0000-0001-6114-9173
Yang, Jinyi0000-0001-5287-4242
Additional Information:© ESO 2022. Received: 9 December 2021 Accepted: 6 March 2022. We are grateful to the referee for their useful and thorough report that helped to improve the manuscript. This work is based on observations carried out under project numbers S052, X04D, S15DA, S17CD, S18DM, S19DM with the IRAM NOEMA Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain). The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation program under grant agreement No 730562 [RadioNet]. R.D. is grateful to the IRAM staff and local contacts for their help and support in the data processing. F.W. and B.P.V. acknowledge support from ERC Advanced grant 740246 (Cosmic_Gas). D.R. acknowledges support from the National Science Foundation under grant numbers AST-1614213 and AST-1910107. D.R. also acknowledges support from the Alexander von Humboldt Foundation through a Humboldt Research Fellowship for Experienced Researchers. F.B. acknowledges support through the within the Collaborative Research Centre 956, sub-project A01, funded by the Deutsche Forschungsgemeinschaft (DFG) – project ID 184018867.
Funding AgencyGrant Number
Institut national des sciences de l'Univers (INSU)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Max Planck SocietyUNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
European Research Council (ERC)730562
European Research Council (ERC)740246
Alexander von Humboldt FoundationUNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)184018867
Subject Keywords:galaxies: high-redshift / galaxies: evolution / galaxies: ISM / galaxies: star formation / quasars: emission lines
Record Number:CaltechAUTHORS:20220721-8510000
Persistent URL:
Official Citation:Molecular gas in z ∼ 6 quasar host galaxies Roberto Decarli, Antonio Pensabene, Bram Venemans, Fabian Walter, Eduardo Bañados, Frank Bertoldi, Chris L. Carilli, Pierre Cox, Xiaohui Fan, Emanuele Paolo Farina, Carl Ferkinhoff, Brent A. Groves, Jianan Li, Chiara Mazzucchelli, Roberto Neri, Dominik A. Riechers, Bade Uzgil, Feige Wang, Ran Wang, Axel Weiss, Jan Martin Winters and Jinyi Yang A&A, 662 (2022) A60 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115736
Deposited By: George Porter
Deposited On:22 Jul 2022 15:10
Last Modified:22 Jul 2022 15:10

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