Planck ’ s Dusty GEMS : Gravitationally lensed high - redshift galaxies discovered with the Planck survey ?

We present an analysis of CO spectroscopy and infrared-to-millimetre dust photometry of 11 bright far-infrared/submillimetre sources discovered through a combination of the Planck all-sky survey and follow-up Herschel-SPIRE imaging – “Planck’s Dusty Gravitationally Enhanced subMillimetre Sources.” Each source has a spectroscopic redshift z = 2.2–3.6 from a blind redshift search with EMIR at the IRAM 30-m telescope. Interferometry obtained at IRAM and the SMA, and optical/near-infrared imaging obtained at the CFHT and the VLT reveal morphologies consistent with strongly gravitationally lensed sources. Additional photometry was obtained with JCMT/SCUBA-2 and IRAM/GISMO at 850 μm and 2 mm, respectively. The spectral energy distributions of our sources peak near either the 350 μm or 500 μm bands of SPIRE. All objects are bright, isolated point sources in the 18′′ beam of SPIRE at 250 μm, with apparent far-infrared luminosities of up to 3× 1014 L (not correcting for the lensing effect). Their morphologies and sizes, CO line widths and luminosities, dust temperatures, and far-infrared luminosities provide additional empirical evidence that these are strongly gravitationally lensed high-redshift galaxies on the submm sky. We discuss their dust masses and temperatures, and use additional WISE 22-μm photometry and template fitting to rule out a significant contribution of AGN heating to the total infrared luminosity. Six sources are detected in FIRST at 1.4 GHz. Four have flux densities brighter than expected from the local far-infrared-radio correlation, but in the range previously found for high-z submm galaxies, one has a deficit of FIR emission, and 6 are consistent with the local correlation, although this includes 3 galaxies with upper limits. The global dust-to-gas ratios and star-formation efficiencies of our sources are predominantly in the range expected from massive, metal-rich, intense, high-redshift starbursts. An extensive multi-wavelength follow-up programme is being carried out to further characterize these sources and the intense star-formation within them.