Molecular gas cloud properties at z ≃ 1 revealed by the superb angular resolution achieved with ALMA and gravitational lensing

Article Article scientifique Article Molecular gas cloud properties at z ≃ 1 revealed by the superb angular resolution achieved with ALMA and gravitational lensing eng 2023-01-13 2023-03-17 author Dessauges Miroslava 0000-0003-0348-2917 517647 Département d'astronomie (ASTRO) author Richard Johan 0000-0001-5492-1049 553414 author Combes Françoise author Messa Matteo 0000-0003-1427-2456 922779 author Nagy David 821313 Département d'astronomie (ASTRO) author Mayer Lucio author Schaerer Daniel Olivier 23688 Département d'astronomie (ASTRO) author Egami Eiichi author Adamo Angela 6222-6238 10.1093/mnras/stad113 0035-8711 https://academic.oup.com/mnras/article/519/4/6222/6987285 <p>Current observations favour that the massive ultraviolet-bright clumps with a median stellar mass of $\sim 10^7\, {\rm M}_{\odot }$, ubiquitously observed in z ∼ 1–3 galaxies, are star-forming regions formed in situ in galaxies. It has been proposed that they result from gas fragmentation due to gravitational instability of gas-rich, turbulent, and high-redshift discs. We bring support to this scenario by reporting the new discovery of giant molecular clouds (GMCs) in the strongly lensed, clumpy, main-sequence galaxy, A521-sys1, at z = 1.043. Its CO(4–3) emission was mapped with the Atacama Large Millimetre/submillimetre Array (ALMA) at an angular resolution of 0.19 × 0.16 arcsec2, reading down to 30 pc, thanks to gravitational lensing. We identified 14 GMCs, most being virialized, with $10^{5.9}-10^{7.9}\, {\rm M}_{\odot }$ masses and a median $800\, {\rm M}_{\odot }~\mathrm{pc}^{-2}$ molecular gas mass surface density, that are, respectively, 100 and 10 times higher than for nearby GMCs. They are also characterized by 10 times higher supersonic turbulence with a median Mach number of 60. They end up to fall above the Larson scaling relations, similarly to the GMCs in another clumpy z ≃ 1 galaxy, the Cosmic Snake, although differences between the two sets of high-redshift GMCs exist. Altogether they support that GMCs form with properties that adjust to the ambient interstellar medium conditions prevalent in the host galaxy whatever its redshift. The detected A521-sys1 GMCs are massive enough to be the parent gas clouds of stellar clumps, with a relatively high star formation efficiency per free-fall time of ∼11 per cent.</p> Gravitational lensing: strong Galaxies: high-redshift Galaxies: individual: A521-sys1 Galaxies: ISM Galaxies: star formation Dewey 520 ESO NSF NINS NRC MOST KASI 2019-00502 26 Département d'astronomie 12 false Monthly notices of the Royal Astronomical Society 519 4 6eab9a84-2baa-42e4-ade6-bedf9bae21f3 Article (Published version) Public Article_scientifique_from_crossref.pdf 2855446 application/pdf CC BY-4.0 bf699b850c3884030863ea6eb0831b6f936aad2e0b46cf4e6efce191d77820c9 openAccess Faculté des sciences / Département d'astronomie

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Molecular gas cloud properties at z ≃ 1 revealed by the superb angular resolution achieved with ALMA and gravitational lensing	Monthly notices of the Royal Astronomical Society			2023	18	9

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