We present the stellar mass (M * ) and Wide-Field Infrared Survey Explorer (WISE) absolute Band 1 magnitude (M W 1 ) Tully-Fisher relations (TFRs) of subsets of galaxies from the CO Legacy Database for the Galex Arecibo SDSS Survey (COLD GASS). We examine the benefits and drawbacks of several commonly used fitting functions in the context of measuring CO(1-0) line widths (and thus rotation velocities), favouring the Gaussian Double Peak function. We find the M W 1 and M * TFR, for a carefully selected sub-sample, to bewhere W 50 is the width of a galaxy's CO(1-0) integrated profile at 50% of its maximum and the inclination i is derived from the galaxy axial ratio measured on the SDSS rband image. We find no evidence for any significant offset between the TFRs of COLD GASS galaxies and those of comparison samples of similar redshifts and morphologies. The slope of the COLD GASS M * TFR agrees with the relation of Pizagno et al. (2005). However, we measure a comparatively shallower slope for the COLD GASS M W 1 TFR as compared to the relation of Tully & Pierce (2000). We attribute this to the fact that the COLD GASS sample comprises galaxies of various (late-type) morphologies. Nevertheless, our work provides a robust reference point with which to compare future CO TFR studies.

We present interferometric observations of CO lines ( 12 CO(1-0, 2-1) and 13 CO(1-0, 2-1)) and dense gas tracers (HCN(1-0), HCO + (1-0), HNC(1-0) and HNCO(4-3)) in two nearby edgeon barred lenticular galaxies, NGC 4710 and NGC 5866, with most of the gas concentrated in a nuclear disc and an inner ring in each galaxy. We probe the physical conditions of a two-component molecular interstellar medium in each galaxy and each kinematic component by using molecular line ratio diagnostics in three complementary ways. First, we measure the ratios of the position-velocity diagrams of different lines, second we measure the ratios of each kinematic component's integrated line intensities as a function of projected position, and third we model these line ratios using a non-local thermodynamic equilibrium radiative transfer code. Overall, the nuclear discs appear to have a tenuous molecular gas component that is hotter, optically thinner and with a larger dense gas fraction than that in the inner rings, suggesting more dense clumps immersed in a hotter more diffuse molecular medium. This is consistent with evidence that the physical conditions in the nuclear discs are similar to those in photo-dissociation regions. A similar picture emerges when comparing the observed molecular line ratios with those of other galaxy types. The physical conditions of the molecular gas in the nuclear discs of NGC 4710 and NGC 5866 thus appear intermediate between those of spiral galaxies and starbursts, while the star formation in their inner rings is even milder.

In this paper we use observations of molecular tracers in metal rich and α-enhanced galaxies to study the effect of abundance changes on molecular chemistry. We selected a sample of metal rich spiral and star bursting objects from the literature, and present here new data for a sample of early-type galaxies (ETGs) previously studied by Crocker et al. (2012). We conducted the first survey of CS and methanol emission in ETGs, detecting 7 objects in at least one CS transition, and methanol emission in 5 ETGs. We find that ETGs whose gas is dominated by ionisation from star-formation have enhanced CS emission, compared to their HCN emission, supporting the hypothesis that CS is a better tracer of dense star-forming gas than HCN. We suggest that the methanol emission in these sources is driven by dust mantle destruction due to ionisation from high mass star formation in dense molecular clouds, but cannot rule out a component due to shocks dominating in some sources. We construct rotation diagrams for each early-type source where at least two transitions of a given species were detected. The rotational temperatures we derive for linear molecules vary between 3 and 9 K, with the majority of sources having rotational temperatures around 5 K. Despite the large uncertainty inherent in this method, the derived source averaged CS and methanol column densities are similar to those found by other authors for normal spiral and starburst galaxies. This may suggest dense clouds are little affected by the differences between early and late type galaxies. Finally we used the total column density ratios for both our ETG and literature galaxy sample to show for the first time that some molecular tracers do seem to show systematic variations that appear to correlate with metallicity, and that these variations roughly match those predicted by chemical models. Using this fact, the chemical models of Bayet et al. (2012b), and assumptions about the optical depth we are able to roughly predict the metallicity of our spiral and ETG sample, with a scatter of ≈0.3 dex. We provide the community with linear approximations to the relationship between the HCN and CS column density ratio and metallicity. Further study will clearly be required to determine if this, or any, molecular tracer can be used to robustly determine gas-phase metallically, but that a relationship exists at all suggests that in the future it may be possible to calibrate a metallicity indicator for the molecular interstellar medium.

The Tully-Fisher relation (TFR) is an empirical relation between galaxy luminosity and rotation velocity. We present here the first TFR of galaxies beyond the local Universe that uses carbon monoxide (CO) as the kinematic tracer. Our final sample includes 25 isolated, non-interacting star-forming galaxies with double-horned or boxy CO integrated line profiles located at redshifts z 0.3, drawn from a larger ensemble of 67 detected objects. The best reverse K s -band, stellar mass and baryonic mass CO TFRs are respec-where M Ks is the total absolute K s -band magnitude of the objects, M ⋆ and M b their total stellar and baryonic masses, and W 50 the width of their line profile at 50% of the maximum. Dividing the sample into different redshift bins and comparing to the TFRs of a sample of local (z = 0) star-forming galaxies from the literature, we find no significant evolution in the slopes and zero-points of the TFRs since z ≈ 0.3, this in either luminosity or mass. In agreement with a growing number of CO TFR studies of nearby galaxies, we more generally find that CO is a suitable and attractive alternative to neutral hydrogen (H I). Our work thus provides an important benchmark for future higher redshift CO TFR studies.