Planck's dusty GEMS: IV. Star formation and feedback in a maximum starburst at z = 3 seen at 60-pc resolution

R. Cañameras, N. Nesvadba, R. Kneissl, B. Frye, R. Gavazzi, S. Koenig, E. Le Floc'h, M. Limousin, I. Oteo, D. Scott

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


We present an analysis of high-resolution ALMA interferometry of CO(4-3) line emission and dust continuum in the "Ruby" (PLCK-G244.8+54.9), a bright, gravitationally lensed galaxy at z = 3.0 discovered with the Planck all-sky survey. The Ruby is the brightest of Planck's dusty GEMS, a sample of 11 of the brightest gravitationally lensed high-redshift galaxies on the extragalactic sub-mm sky. We resolve the high-surface-brightness continuum and CO line emission of the Ruby in several extended clumps along a partial, nearly circular Einstein ring with 1.4′′ diameter around a massive galaxy at z = 1.5. Local star-formation intensities are up to 2000 MȮ yr-1 kpc-2, amongst the highest observed at high redshift, and clearly in the range of maximal starbursts. Gas-mass surface densities are a few × 104MȮ pc-2. The Ruby lies at, and in part even above, the starburst sequence in the Schmidt-Kennicutt diagram, and at the limit expected for star formation that is self-regulated through the kinetic energy injection from radiation pressure, stellar winds, and supernovae. We show that these processes can also inject sufficient kinetic energy and momentum into the gas to explain the turbulent line widths, which are consistent with marginally gravitationally bound molecular clouds embedded in a critically Toomre-stable disk. The star-formation efficiency is in the range 1-10% per free-fall time, consistent with the notion that the pressure balance that sets the local star-formation law in the Milky Way may well be universal out to the highest star-formation intensities. AGN feedback is not necessary to regulate the star formation in the Ruby, in agreement with the absence of a bright AGN component in the infrared and radio regimes.

Original languageEnglish (US)
Article numberA117
JournalAstronomy and astrophysics
StatePublished - Aug 1 2017


  • Galaxies: ISM
  • Galaxies: evolution
  • Galaxies: high-redshift
  • Galaxies: star formation
  • Galaxies: starburst
  • Submillimeter: galaxies

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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