We present Herschel -SPIRE Fourier Transform Spectrometer (FTS) and radio followup observations of two Herschel -ATLAS (H-ATLAS) detected strongly lensed distant galaxies. In one of the targeted galaxies H-ATLAS J090311.6+003906 (SDP.81) we detect [O iii] 88 µm and [C ii] 158 µm lines at a signal-to-noise ratio of ∼ 5. We do not have any positive line identification in the other fainter target H-ATLAS J091305.0−005343 (SDP.130). Currently SDP.81 is the faintest sub-mm galaxy with positive line detections with the FTS, with continuum flux just below 200 mJy in the 200-600 µm wavelength range. The derived redshift of SDP.81 from the two detections is z = 3.043 ± 0.012, in agreement with ground-based CO measurements. This is the first detection by Herschel of the [O iii] 88 µm line in a galaxy at redshift higher than 0.05. Comparing the observed lines and line ratios with a grid of photo-dissociation region (PDR) models with different physical conditions, we derive the PDR cloud density n ≈ 2000 cm −3 and the far-UV ionizing radiation field G 0 ≈ 200 (in units of the Habing field -the local Galactic interstellar radiation field of 1.6 × 10 −6 W m −2 ). Using the CO derived molecular mass and the PDR properties we estimate the effective radius of the emitting region to be 500-700 pc. These characteristics are typical for star-forming, high redshift galaxies. The radio observations indicate that SDP.81 deviates significantly from the local FIR/radio correlation, which hints that some fraction of the radio emission is coming from an AGN. The constraints on the source size from millimiter-wave observations put a very conservative upper limit of the possible AGN contribution to less than 33%. These indications, together with the high [O iii]/FIR ratio and the upper limit of [O i] 63 µm/[C ii] 158 µm suggest that some fraction of the ionizing radiation is likely to originate from an AGN.

We use galaxies from the Herschel-ATLAS survey, and a suite of ancillary simulations based on an isothermal dust model, to study our ability to determine the effective dust temperature, luminosity and emissivity index of 250 µm selected galaxies in the local Universe (z < 0.5). As well as simple far-infrared SED fitting of individual galaxies based on χ 2 minimisation, we attempt to derive the best global isothermal properties of 13,826 galaxies with reliable optical counterparts and spectroscopic redshifts. Using our simulations, we highlight the fact that applying traditional SED fitting techniques to noisy observational data in the Herschel Space Observatory bands introduces artificial anti-correlation between derived values of dust temperature and emissivity index. This is true even for galaxies with the most robust statistical detections in our sample, making the results of such fitting difficult to interpret. We apply a method to determine the best-fit global values of isothermal effective temperature and emissivity index for z < 0.5 galaxies in H-ATLAS, deriving T eff = 22.3±0.1 K and β = 1.98±0.02 (or T eff = 23.5 ± 0.1 K and β = 1.82 ± 0.02 if we attempt to correct for bias by assuming that T eff and β eff are independent and normally distributed). We use our technique to test for an evolving emissivity index, finding only weak evidence. The median dust luminosity of our sample is log 10 (L dust /L ⊙ ) = 10.72 ± 0.05, which (unlike T eff ) shows little dependence on the choice of β used in our analysis, including whether it is variable or fixed. In addition, we use a further suite of simulations based on a fixed emissivity index isothermal model to emphasize the importance of the H-ATLAS PACS data for deriving dust temperatures at these redshifts, even though they are considerably less sensitive than the SPIRE data. Finally, we show that the majority of galaxies detected by H-ATLAS are normal star-forming galaxies, though with a substantial minority (∼ 31 per cent) falling in the Luminous Infrared Galaxy category.

We have constructed a sample of radio-loud objects with optical spectroscopy from the Galaxy and Mass Assembly (GAMA) project over the Herschel Astrophysical Terahertz Large Area Survey (Herschel-ATLAS) Phase 1 fields. Classifying the radio sources in terms of their optical spectra, we find that strong-emission-line sources ('high-excitation radio galaxies') have, on average, a factor of ∼4 higher 250-μm Herschel luminosity than weak-line ('lowexcitation') radio galaxies and are also more luminous than magnitude-matched radio-quiet galaxies at the same redshift. Using all five H-ATLAS bands, we show that this difference in luminosity between the emission-line classes arises mostly from a difference in the average dust temperature; strong-emission-line sources tend to have comparable dust masses to, but higher dust temperatures than, radio galaxies with weak emission lines. We interpret this as showing that radio galaxies with strong nuclear emission lines are much more likely to be associated with star formation in their host galaxy, although there is certainly not a one-to-one relationship between star formation and strong-line active galactic nuclei (AGN) activity. The strong-line sources are estimated to have star formation rates at least a factor of 3-4 higher than Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

We present observations of the nearby spiral galaxy IC342 with the Herschel Spectral and Photometric Imaging Receiver (SPIRE) Fourier Transform Spectrometer. The spectral range afforded by SPIRE, 196-671 µm, allows us to access a number of 12 CO lines from J=4-3 to J=13-12 with the highest J transitions observed for the first time. In addition we present measurements of 13 CO, [CI] and [NII]. We use a radiative transfer code coupled with Bayesian likelihood analysis to model and constrain the temperature, density and column density of the gas. We find two 12 CO components, one at 35 K and one at 400 K with CO column densities of 6.3×10 17 cm −2 and 0.4×10 17 cm −2 and CO gas masses of 1.26×10 7 M and 0.15×10 7 M , for the cold and warm components, respectively. The inclusion of the high-J 12 CO line observations, indicate the existence of a much warmer gas component (∼400 K) confirming earlier findings from H 2 rotational line analysis from ISO and Spitzer. The mass of the warm gas is 10% of the cold gas, but it likely dominates the CO luminosity. In addition, we detect strong emission from [NII] 205 µm and the 3 P 1 → 3 P 0 and 3 P 2 → 3 P 1 [CI] lines at 370 and 608 µm, respectively. The measured 12 CO line ratios can be explained by Photon-dominated region (PDR) models although additional heating by e.g. cosmic rays cannot be excluded. The measured [CI] line ratio together with the derived [C] column density of 2.1×10 17 cm −2 and the fact that [CI] is weaker than CO emission in IC342 suggests that [CI] likely arises in a thin layer on the outside of the CO emitting molecular clouds consistent with PDRs playing an important role.