RT Journal Article
T1 Molecular clouds in the Cosmic Snake normal star-forming galaxy 8 billion years ago
A1 Pérez González, Pablo Guillermo
AB The cold molecular gas in contemporary galaxies is structured in discrete cloud complexes. These giant molecular clouds (GMCs), with 10^(4) –10^(7) solar masses (M⊙) and radii of 5–100 parsecs, are the seeds of star formation1 . Highlighting the molecular gas structure at such small scales in distant galaxies is observationally challenging. Only a handful of molecular clouds were reported in two extreme submillimetre galaxies at high redshift(2-4) . Here we search for GMCs in a typical Milky Way progenitor at z=1.036. Using the Atacama Large Millimeter/submillimeter Array (ALMA), we mapped the CO(4–3) emission of this gravitationally lensed galaxy at high resolution, reading down to 30 parsecs, which is comparable to the resolution of CO observations of nearby galaxies(5). We identify 17 molecular clouds, characterized by masses, surface densities and supersonic turbulence all of which are 10–100 times higher than present-day analogues. These properties question the universality of GMCs(6) and suggest that GMCs inherit their properties from ambient interstellar medium. The measured cloud gas masses are similar to the masses of stellar clumps seen in the galaxy in comparable numbers(7) . This corroborates the formation of molecular clouds by fragmentation of distant turbulent galactic gas disks(8,9), which then turn into stellar clumps ubiquitously observed in galaxies at ‘cosmic noon’ (ref. 10).
PB Nature Publishing Group
SN 2397-3366
YR 2019
FD 2019-12
LK https://hdl.handle.net/20.500.14352/6056
UL https://hdl.handle.net/20.500.14352/6056
LA eng
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The nature of giant clumps in distantgalaxies probed by the anatomy of the Cosmic Snake.Nat. Astron. 2, 76–82 (2018)given molecular cloud by the hydrostatic pressure at thedisk midplane for a two-component disk of gas and stars45:ÉYçnÑ = é2 G Σ89: ;Σ89: +%89:%:n9Q:Σ:n9Q:G cmlOKwhere Σ89:, Σ:n9Q:, and %89:, %:n9Q: are the surfacedensities and velocity dispersions of the gas and stars,respectively. We considered the molecular gas phase as thedominant phase of the neutral (atomic + molecular) gas inthis z≃1 galaxy. We derived surface densities from themolecular gas and stellar masses contained within theobserved gas disk of 1.7kpc in galactocentric radius, andassumed the velocity dispersions of gas and stars to becomparable. We obtained the hydrostatic pressure of~107.7 cm−3K in the Cosmic Snake galaxy.Data availabilityThe ALMA raw data of the Cosmic Snake arc are availablethrough the ALMA archive under the project identification2013.1.01330.S. 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NO © The Autors, 2019. Artículo firmado por 15 autores. The work of M.D.-Z., D.S., L.M. and A.C. was supported by the STARFORM Sinergia Project funded by the Swiss National Science Foundation. J.R. acknowledges support from the European Research Council starting grant 336736-CALENDS. W.R. is supported by the Thailand Research Fund/Office of the Higher Education Commission Grant Number MRG6280259 and Chulalongkorn University’s CUniverse. P.G.P.-G. acknowledges support from the Spanish Government grant AYA2015-63650-P. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2013.1.01330.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada), MOST and ASIAA (Taiwan), and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. We also used PdBI observations. PdBI is run by the Institut de Radioastronomie Millimétrique (IRAM, France), a partnership of the French CNRS, the German MPG and the Spanish IGN. Part of the analysis presented herein is also based on observations made with the NASA/ESA Hubble Space Telescope, and obtained from the Hubble Legacy Archive, which is a collaboration between the Space Telescope Science Institute (STScI/NASA), the Space Telescope European Coordinating Facility (ST-ECF/ESA) and the Canadian Astronomy Data Centre (CADC/NRC/CSA). We thank E. Chapillon from the ALMA Regional Center node of IRAM for her help and training on the reduction of the ALMA data, V. Patricio for sharing the kinematic analysis of the [OII] emission of the Cosmic Snake galaxy and C. Georgy for the presentation of the VisIt 3D visualization tool.
NO Unión Europea. FP7
NO Ministerio de Economía y Competitividad (MINECO)
NO Swiss National Science Foundation
NO Thailand Research Fund/Office of the Higher Education Commission
NO Chulalongkorn University’s CUniverse
NO NSF (USA)
NO NINS (Japan)
NO NRC (Canada)
NO MOST and ASIAA (Taiwan)
NO KASI (Republic of Korea)
NO Republic of Chile
NO Institut de Radioastronomie Millimétrique (IRAM, France)
NO French CNRS
NO German MPG
NO Spanish IGN
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