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Molecular gas in AzTEC/C159: a star-forming disk galaxy 1.3 Gyr after the Big Bang

Jiménez-Andrade, E. F. and Capak, P. L. (2018) Molecular gas in AzTEC/C159: a star-forming disk galaxy 1.3 Gyr after the Big Bang. Astronomy and Astrophysics, 615 . Art. No. A25. ISSN 0004-6361.

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We studied the molecular gas properties of AzTEC/C159, a star-forming disk galaxy at z = 4.567, in order to better constrain the nature of the high-redshift end of the submillimeter-selected galaxy (SMG) population. We secured ^(12)CO molecular line detections for the J = 2 →1 and J = 5 →4 transitions using the Karl G. Jansky Very Large Array (VLA) and the NOrthern Extended Millimeter Array (NOEMA) interferometer. The broad (FWHM ~ 750 km s^(−1)) and tentative double-peaked profiles of the two ^(12)CO lines are consistent with an extended molecular gas reservoir, which is distributed in a rotating disk, as previously revealed from [CII] 158 μm line observations. Based on the 12CO(2 →1) emission line, we derived L′_(CO)=(3.4±0.6)×10^(10) K km s^(−1) pc^2, which yields a molecular gas mass of M_(H2)(α_(CO)/4.3)=(1.5±0.3)×10^(11) M⊙ and unveils a gas-rich system with μ_(gas)(α_(CO)/4.3)≡M_(H2)/M⋆=3.3±0.7. The extreme star formation efficiency of AzTEC/C159, parametrized by the ratio L_(IR)/L′_(CO)=(216±80) L⊙ (K km s^(−1) pc^2)^(−1), is comparable to merger-driven starbursts such as local ultra-luminous infrared galaxies and SMGs. Likewise, the ^(12)CO(5 →4)/CO(2 →1) line brightness temperature ratio of r_(52)= 0.55 ± 0.15 is consistent with high-excitation conditions as observed in SMGs. Based on mass budget considerations, we constrained the value for the L′_(CO) – H_2 mass conversion factor in AzTEC/C159, that is, α_(CO)=3.9_(−1.3)^(+2.7) M⊙ K^(−1) km^(−1) s pc^(−2), which is consistent with a self-gravitating molecular gas distribution as observed in local star-forming disk galaxies. Cold gas streams from cosmological filaments might be fueling a gravitationally unstable gas-rich disk in AzTEC/C159, which breaks into giant clumps and forms stars as efficiently as in merger-driven systems and generates high gas excitation. These results support the evolutionary connection between AzTEC/C159-like systems and massive quiescent disk galaxies at z ~ 2.

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Jiménez-Andrade, E. F.0000-0002-2640-5917
Additional Information:© 2018 ESO. Article published by EDP Sciences. Received 27 October 2017; Accepted 9 February 2018; Published online 05 July 2018. We thank Ian Smail for his detailed comments and suggestions that helped to improve the manuscript. E.F.J.A would like to thank M. Krips for her support during the visit to IRAM/Grenoble and the hospitality of the DSOC in Socorro/New Mexico. Support for B.M. was provided by the DFG priority program 1573 “The physics of the interstellar medium”. G.C.J. is grateful for support from NRAO through the Grote Reber Doctoral Fellowship Program. E.F.J.A, B.M., A.K., E.R.D. and F.B. acknowledge support of the Collaborative Research Center 956, subproject A1 and C4, funded by the Deutsche Forschungsgemeinschaft (DFG). C.G.G and S.T. acknowledge support from the European Research Council (ERC) Consolidator Grant funding scheme (project ConTExt, grant number: 648179). D.R. acknowledges support from the National Science Foundation under grant number AST-1614213. M.A. acknowledges partial support from FONDECYT through grant 1140099. M.J.M. acknowledges the support of the National Science Centre, Poland through the POLONEZ grant 2015/19/P/ST9/04010; this project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 665778. V.S. acknowledges support from the European Union’s Seventh Frame-work program under grant agreement 337595 (ERC Starting Grant, “CoSMass”). The National Radio Astronomy Observatory (NRAO) is operated by Associated Universities, Inc., under cooperative agreement with the National Science Foundation. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).
Group:COSMOS, Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)1573
National Radio Astronomy ObservatoryUNSPECIFIED
Deutsche Forschungsgemeinschaft (DFG)956
European Research Council (ERC)648179
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1140099
National Science Centre (Poland)2015/19/P/ST9/04010
Marie Curie Fellowship665778
European Research Council (ERC)337595
Institute for Studies in Theoretical Physics and Mathematics (Iran)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Instituto Geográfico Nacional (IGN)UNSPECIFIED
Subject Keywords:galaxies: high-redshift – galaxies: formation – galaxies: ISM – ISM: molecules
Record Number:CaltechAUTHORS:20180719-083430626
Persistent URL:
Official Citation:Molecular gas in AzTEC/C159: a star-forming disk galaxy 1.3 Gyr after the Big Bang E. F. Jiménez-Andrade, B. Magnelli, A. Karim, G. C. Jones, C. L. Carilli, E. Romano-Díaz, C. Gómez-Guijarro, S. Toft, F. Bertoldi, D. A. Riechers, E. Schinnerer, M. Sargent, M. J. Michałowski, F. Fraternali, J. G. Staguhn, V. Smolčić, M. Aravena, K. C. Harrington, K. Sheth, P. L. Capak, A. M. Koekemoer, E. van Kampen, M. Swinbank, A. Zirm, G. E. Magdis and F. Navarrete A&A, 615 (2018) A25 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87990
Deposited By: Tony Diaz
Deposited On:19 Jul 2018 17:51
Last Modified:19 Jul 2018 17:51

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