Volume 604, August 2017
|Number of page(s)||11|
|Published online||23 August 2017|
Planck’s dusty GEMS
IV. Star formation and feedback in a maximum starburst at z = 3 seen at 60-pc resolution⋆
1 Institut d’Astrophysique Spatiale, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Bât. 121, 91405 Orsay Cedex, France
2 European Southern Observatory, ESO Vitacura, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago, Chile
3 Atacama Large Millimeter/submillimeter Array, ALMA Santiago Central Offices, Alonso de Cordova 3107, Vitacura, Casilla 763-0355, Santiago, Chile
4 Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
5 Institut d’Astrophysique de Paris, 75014 Paris, UPMC Université Paris 6, UMR7095, France
6 Chalmers University of Technology, Onsala Space Observatory, Onsala, Sweden
7 Laboratoire AIM, CEA/DSM/IRFU, CNRS, Universite Paris-Diderot, Bat. 709, 91191 Gif-sur-Yvette, France
8 Aix Marseille Univ, CNRS, LAM, Laboratoire d’Astrophysique de Marseille, 13013 Marseille, France
9 Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, UK
10 European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
11 Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, 6658 British Columbia, Canada
⋆⋆ Corresponding author: R. Cañameras, firstname.lastname@example.org
Received: 2 December 2016
Accepted: 24 March 2017
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 M⊙ 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 × 104M⊙ 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.
Key words: galaxies: starburst / galaxies: high-redshift / submillimeter: galaxies / galaxies: evolution / galaxies: star formation / galaxies: ISM
© ESO, 2017
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