ALMA resolves turbulent, rotating [CII] emission in a young starburst galaxy at z=4.8

Carlos De Breuck, Rebecca J. Williams, Mark Swinbank, Paola Caselli, Kristen Coppin, Timothy A. Davis, Roberto Maiolino, Tohru Nagao, Ian Smail, Fabian Walter, Axel Weiss, Martin Zwaan

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Abstract

We present spatially resolved Atacama Large Millimeter/submillimeter Array (ALMA) [CII] observations of the z=4.7555 submillimetre galaxy, ALESS 73.1. Our 0.5" FWHM map resolves the [CII] emitting gas which is centred close to the active galactic nucleus (AGN). The gas kinematics are dominated by rotation but with high turbulence, v_rot/sigma_int~3.1, and a Toomre Q parameter alpha_CO ~0.4. The diameter of the dust continuum emission is 80 Gyr^{-1}, especially since there are no clear indications of recent merger activity. Finally, our high signal-to-noise [CII] measurement revises the observed [NII]/[CII] ratio, which suggests a close to solar metallicity, unless the [CII] flux contains significant contributions from HII regions. Our observations suggest that ALESS73.1 is a nascent galaxy undergoing its first major burst of star formation, embedded within an unstable but metal-rich gas disk.
Original languageEnglish
Article numberA59
Number of pages10
JournalAstronomy & Astrophysics
Volume565
Early online date12 May 2014
DOIs
Publication statusPublished - 31 May 2014

Keywords

  • galaxies: high-redshift
  • galaxies: starburst
  • galaxies: kinematics and dynamics
  • galaxies: ISM

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