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Abstract:

Abstract We study the dust properties of 192 nearby galaxies from the JINGLE survey using photometric data in the 22-850$\mu$m range. We derive the total dust mass, temperature T and emissivity index β of the galaxies through the fitting of their spectral energy distribution (SED) using a single modified black-body model (SMBB). We apply a hierarchical Bayesian approach that reduces the known degeneracy between T and β. Applying the hierarchical approach, the strength of the T-β anti-correlation is reduced from a Pearson correlation coefficient R = −0.79 to R = −0.52. For the JINGLE galaxies we measure dust temperatures in the range 17 − 30 K and dust emissivity indices β in the range 0.6 − 2.2. We compare the SMBB model with the broken emissivity modified black-body (BMBB) and the two modified black-bodies (TMBB) models. The results derived with the SMBB and TMBB are in good agreement, thus applying the SMBB, which comes with fewer free parameters, does not penalize the measurement of the cold dust properties in the JINGLE sample. We investigate the relation between T and β and other global galaxy properties in the JINGLE and Herschel Reference Survey (HRS) sample. We find that β correlates with the stellar mass surface density (R = 0.62) and anti-correlates with the HI mass fraction (MHI/M*, R = −0.65), whereas the dust temperature correlates strongly with the SFR normalized by the dust mass (R = 0.73). These relations can be used to estimate T and β in galaxies with insufficient photometric data available to measure them directly through SED fitting.

Abstract:

We present an analysis of the gas outflow energetics from KMOS observations of ∼ 529 main-sequence star-forming galaxies at z ∼ 1 using broad, underlying H α and forbidden lines of [N II] and [S II]. Based on the stacked spectra for a sample with median star-formation rates and stellar masses of SFR = 7 M⊙   yr−1 and M⋆ = (1.0 ± 0.1) × 1010 M⊙, respectively, we derive a typical mass outflow rate of M˙wind = 1–4 M⊙ yr−1 and a mass loading of M˙wind / SFR = 0.2–0.4. By comparing the kinetic energy in the wind with the energy released by supernovae, we estimate a coupling efficiency between the star formation and wind energetics of ϵ ∼  0.03. The mass loading of the wind does not show a strong trend with star-formation rate over the range ∼ 2–20 M⊙ yr−1, although we identify a trend with stellar mass such that dM / dt / SFR ∝ M0.26±0.07⋆⁠. Finally, the line width of the broad H α increases with disc circular velocity with a sub-linear scaling relation FWHMbroad ∝ v0.21 ± 0.05. As a result of this behaviour, in the lowest mass galaxies (M⋆ ≲ 1010 M⊙), a significant fraction of the outflowing gas should have sufficient velocity to escape the gravitational potential of the halo whilst in the highest mass galaxies (M⋆ ≳ 1010 M⊙) most of the gas will be retained, flowing back on to the galaxy disc at later times.