Context. The submillimetre-bright galaxy population is believed to comprise, aside from local galaxies and radio-loud sources, intrinsically active star-forming galaxies, the brightest of which are lensed gravitationally. The latter enable studies at a level of detail beyond what is usually possible by the observation facility. Aims. This work focuses on one of these lensed systems, HATLAS J142935.3−002836 (H1429−0028), selected in the Herschel-ATLAS field. Gathering a rich, multi-wavelength dataset, we aim to confirm the lensing hypothesis and model the background source's morphology and dynamics, as well as to provide a full physical characterisation. Methods. Multi-wavelength high-resolution data is utilised to assess the nature of the system. A lensing-analysis algorithm that simultaneously fits different wavebands is adopted to characterise the lens. The background galaxy dynamical information is studied by reconstructing the 3D source plane of the ALMA CO (J:4 → 3) transition. Near-IR imaging from HST and Keck-AO allows to constrain rest-frame optical photometry independently for the foreground and background systems. Physical parameters (such as stellar and dust masses) are estimated via modelling of the spectral energy distribution taking source blending, foreground obscuration, and differential magnification into account. Results. The system comprises a foreground edge-on disk galaxy (at z sp = 0.218) with an almost complete Einstein ring around it. The background source (at z sp = 1.027) is magnified by a factor of μ ∼ 8−10 depending on wavelength. It is comprised of two components and a tens-of-kpc-long tidal tail resembling the Antennae merger. As a whole, the background source is a massive stellar system (1.32 +0.63−0.41 × 10 11 M ) forming stars at a rate of 394 ± 90 M yr −1 , and it has a significant gas reservoir M ISM = 4.6 ± 1.7 × 10 10 M . Its depletion time due to star formation alone is thus expected to be τ SF = M ISM /SFR = 117 ± 51 Myr. The dynamical mass of one of the components is estimated to be 5.8 ± 1.7 × 10 10 M , and, together with the photometric total mass estimate, it implies that H1429−0028 is a major merger system (1:2.8 +1.8 −1.5).

We report 250 GHz (1.2 mm) observations of a sample of 20 quasars at redshifts 5.8 < z < 6.5 from the Canada-France High-z Quasar Survey (CFHQS), using the Max-Planck-Millimeter-Bolometer (MAMBO) array at the 30-metre telescope of the Institut de Radioastronomie Millmétrique (IRAM). An rms sensitivity of 0.6 mJy was achieved for 65% of the sample, and of 1.0 mJy for 90%. Only one quasar, CFHQS J142952+544717, was robustly detected with S 250 GHz = 3.46 ± 0.52 mJy. This indicates that one of the most powerful known starbursts at z ∼ 6 is associated with this radio-loud quasar. On average, the other CFHQS quasars, which have a mean optical magnitude fainter than the previously studied samples of z ∼ 6 quasars of the Sloan Digital Sky Survey (SDSS), have a mean 1.2 mm flux density S 250 GHz = 0.41 ± 0.14 mJy; this average detection with a signal-to-noise (S/N) ratio of 2.9 is hardly meaningful. It would correspond to L FIR ≈ 0.94 ± 0.32 × 10 12 L , and an average star formation rate of a few 100 M /yr, depending on the stellar initial mass function (IMF) and a possible contribution of an active galactic nucleus (AGN) to L FIR . This is consistent with previous findings of Wang et al. on the far-infrared emission of z ∼ 6 quasars and extends their results toward optically fainter sources.

Context. Dust and its emission is being increasingly used to constrain the evolutionary stage of galaxies. A comprehensive characterization of dust, best achieved in nearby bright galaxies, is thus a highly useful resource. Aims. We aim to characterize the relationship between dust properties (mass, luminosity and temperature) and their relationships with galaxy-wide properties (stellar, atomic and molecular gas mass, and star formation mode). We also aim to provide equations to estimate accurate dust properties from limited observational datasets. Methods. We assemble a sample of 1,630 nearby (z < 0.1) galaxies -over a large range of stellar masses (M * ), star formation rates (SFR) and specific star formation rates (sSFR=SFR/M * ) -for which comprehensive and uniform multi-wavelength observations are available from WISE, IRAS, Planck and/or SCUBA. the characterization of dust emission comes from spectral energy distribution (SED) fitting using Draine & Li dust models, which we parametrize using two components (warm at 45 -70 K and cold at 18 -31 K). The subsample of these galaxies with global measurements of CO and/or HI are used to explore the molecular and/or atomic gas content of the galaxies. Results. The total infrared luminosity (L IR ), dust mass (M dust ) and dust temperature of the cold component (T cold ) form a plane that we refer to as the dust plane. A galaxy's sSFR drives its position on the dust plane: starburst (high sSFR) galaxies show higher L IR , M dust and T cold compared to Main Sequence (typical sSFR) and passive galaxies (low sSFR). Starburst galaxies also show higher specific dust masses (M dust /M * ) and specific gas masses ( M gas /M * ). We confirm earlier findings of an anti-correlation between the dust to stellar mass ratio and M * . We also find different anti-correlations depending on sSFR; the anti-correlation becomes stronger as the sSFR increases, with the spread due to different cold dust temperatures. The dust mass is more closely correlated with the total gas mass (atomic plus molecular) than with the individual atomic and molecular gas masses. Our comprehensive multi wavelength data allows us to define several equations to accurately estimate L IR , M dust and T cold from one or two monochromatic luminosities in the infrared and/or sub-millimeter. Conclusions. It is possible to estimate the dust mass and infrared luminosity from a single monochromatic luminosity within the Rayleigh-Jeans tail of the dust emission, with errors of 0.12 and 0.20 dex, respectively. These errors are reduced to 0.05 and 0.10 dex, respectively, if the dust temperature of the cold component is used. The dust mass is better correlated with the total ISM mass ( M ISM ∝ M dust 0.7 ). For galaxies with stellar masses 8.5 < log(M * / M ⊙ ) < 11.9, the conversion factor between the single monochromatic luminosity at 850 µm and the total ISM mass (α 850 µm ) shows a large scatter (rms = 0.29 dex) and a weak correlation with the L IR . The star formation mode of a galaxy shows a correlation with...