Aims. The goal of this paper is to analyse the behaviour of the gas-to-dust mass ratio (G/D) of local Universe galaxies over a wide metallicity range. We especially focus on the low-metallicity part of the G/D vs metallicity relation and investigate several explanations for the observed relation and scatter. Methods. We assembled a total of 126 galaxies, covering a 2 dex metallicity range and with 30% of the sample with 12 + log(O/H) ≤ 8.0. We homogeneously determined the dust masses with a semi-empirical dust model including submm constraints. The atomic and molecular gas masses have been compiled from the literature. We used two X CO scenarios to estimate the molecular gas mass: the Galactic conversion factor, X CO,MW , and a X CO that depends on the metallicity X CO,Z (∝Z −2 ). We modelled the observed trend of the G/D with metallicity using two simple power laws (slope of -1 and free) and a broken power law. Correlations with morphological type, stellar masses, star formation rates, and specific star formation rates are also discussed. We then compared the observed evolution of the G/D with predictions from several chemical evolution models and explored different physical explanations for the observed scatter in the G/D values. Results. We find that out of the five tested galactic parameters, metallicity is the main physical property of the galaxy driving the observed G/D. The G/D versus metallicity relation cannot be represented by a single power law with a slope of -1 over the whole metallicity range. The observed trend is steeper for metallicities lower than ∼8.0. A large scatter is observed in the G/D values for a given metallicity: in metallicity bins of ∼0.1 dex, the dispersion around the mean value is ∼0.37 dex. On average, the broken power law reproduces the observed G/D best compared to the two power laws (slope of -1 or free) and provides estimates of the G/D that are accurate to a factor of 1.6. The good agreement of observed values of the G/D and its scatter with respect to metallicity with the predicted values of the three tested chemical evolution models allows us to infer that the scatter in the relation is intrinsic to galactic properties, reflecting the different star formation histories, dust destruction efficiencies, dust grain size distributions, and chemical compositions across the sample. Conclusions. Our results show that the chemical evolution of low-metallicity galaxies, traced by their G/D, strongly depends on their local internal conditions and individual histories. The large scatter in the observed G/D at a given metallicity reflects the impact of various processes occurring during the evolution of a galaxy. Despite the numerous degeneracies affecting them, disentangling these various processes is now the next step.

The Herschel ATLAS is the largest open-time key project that will be carried out on the Herschel Space Observatory. It will survey 570 deg2 of the extragalactic sky, 4 times larger than all the other Herschel extragalactic surveys combined, in five far-infrared and submillimeter bands. We describe the survey, the complementary multiwavelength data sets that will be combined with the Herschel data, and the six major science programs we are undertaking. Using new models based on a previous submillimeter survey of galaxies, we present predictions of the properties of the ATLAS sources in other wave bands

Galaxies' rest-frame ultraviolet (UV) properties are often used to directly infer the degree to which dust obscuration affects the measurement of star formation rates. While much recent work has focused on calibrating dust attenuation in galaxies selected at rest-frame ultraviolet wavelengths, locally and at high-z, here we investigate attenuation in dusty, star-forming galaxies (DSFGs) selected at farinfrared wavelengths. By combining multiwavelength coverage across 0.15-500 µm in the COSMOS field, in particular making use of Herschel imaging, and a rich dataset on local galaxies, we find a empirical variation in the relationship between rest-frame UV slope (β) and ratio of infrared-toultraviolet emission (L IR /L UV ≡IRX) as a function of infrared luminosity, or total star formation rate, SFR. Both locally and at high-z, galaxies above SFR > ∼ 50 M yr −1 deviate from the nominal IRX-β relation towards bluer colors by a factor proportional to their increasing IR luminosity. We also estimate contamination rates of DSFGs on high-z dropout searches of 1% at z < ∼ 4 − 10, providing independent verification that contamination from very dusty foreground galaxies is low in LBG searches. Overall, our results are consistent with the physical interpretation that DSFGs, e.g. galaxies with > 50 M yr −1 , are dominated at all epochs by short-lived, extreme burst events, producing many young O and B stars that are primarily, yet not entirely, enshrouded in thick dust cocoons. The blue rest-frame UV slopes of DSFGs are inconsistent with the suggestion that most DSFGs at z ∼ 2 exhibit steady-state star formation in secular disks.

We present the Atacama Large Millimeter/submillimeter Array (ALMA) detection of the [O iii] 88 µm line and rest-frame 90 µm dust continuum emission in a Y -dropout Lyman break galaxy (LBG), MACS0416 Y1, lying behind the Frontier Field cluster MACS J0416.1−2403. This [O iii] detection confirms the LBG with a spectroscopic redshift of z = 8.3118 ± 0.0003, making this object one of the furthest galaxies ever identified spectroscopically. The observed 850 µm flux density of 137 ± 26 µJy corresponds to a de-lensed total infrared (IR) luminosity of L IR = (1.7±0.3)×10 11 L if assuming a dust temperature of T dust = 50 K and an emissivity index of β = 1.5, yielding a large dust mass of 4×10 6 M . The ultraviolet-to-far IR spectral energy distribution modeling where the [O iii] emissivity model is incorporated suggests the presence of a young (τ age ≈ 4 Myr), star-forming (SFR ≈ 60 M yr −1 ), moderately metal-polluted (Z ≈ 0.2Z ) stellar component with a mass of M star = 3 × 10 8 M . An analytic dust mass evolution model with a single episode of star-formation does not reproduce the metallicity and dust mass in τ age ≈ 4 Myr, suggesting a pre-existing evolved stellar component with M star ∼ 3 × 10 9 M and τ age ∼ 0.3 Gyr as the origin of the dust mass.

This paper investigates the main driver of dust mass growth in the interstellar medium (ISM) by using a chemical evolution model of a galaxy with metals (elements heavier than helium) in the dust phase, in addition to the total amount of metals. We consider asymptotic giant branch (AGB) stars, type II supernovae (SNe II), and dust mass growth in the ISM, as the sources of dust, and SN shocks as the destruction mechanism of dust. Furthermore, to describe the dust evolution precisely, our model takes into account the age and metallicity (the ratio of metal mass to ISM mass) dependence of the sources of dust. We have particularly focused on the dust mass growth, and found that in the ISM this is regulated by the metallicity. To quantify this aspect, we introduce a "critical metallicity", which is the metallicity at which the contribution of stars (AGB stars and SNe II) equals that of the dust mass growth in the ISM. If the star-formation timescale is shorter, the value of the critical metallicity is higher, but the galactic age at which the metallicity reaches the critical metallicity is shorter. From observations, it was expected that the dust mass growth was the dominant source of dust in the Milky Way and dusty QSOs at high redshifts. By introducing a critical metallicity, it is clearly shown that the dust mass growth is the main source of dust in such galaxies with various star-formation timescales and ages. The dust mass growth in the ISM is regulated by metallicity, and we emphasize that the critical metallicity serves as an indicator to judge whether the grain growth in the ISM is the dominant source of dust in a galaxy, especially because of the strong, and nonlinear, dependence on the metallicity.