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Dust properties and star formation of approximately a thousand local galaxies

Abstract : Aims. We derived the dust properties for 753 local galaxies and examine how these relate to some of their physical properties. We present the derived dust emission properties, including model spectral energy distribution (SEDs), star formation rates (SFRs) and stellar masses, as well as their relations. Methods. We modelled the global dust-SEDs for 753 galaxies, treated statistically as an ensemble within a hierarchical Bayesian dust-SED modelling approach, so as to derive their infrared (IR) emission properties. To create the observed dust-SEDs, we used a multi-wavelength set of observations, ranging from near-IR to far-IR-to-submillimeter wavelengths. The model-derived properties are the dust masses ($M_{dust}$), the average interstellar radiation field intensities ($U_{av}$), the mass fraction of very small dust grains (“QPAH” fraction), as well as their standard deviations. In addition, we used mid-IR observations to derive SFR and stellar masses, quantities independent of the dust-SED modelling. Results. We derive distribution functions of the properties for the galaxy ensemble and as a function of galaxy type. The mean value of $M_{dust}$ for the early-type galaxies (ETGs) is lower than that for the late-type and irregular galaxies (LTGs and Irs, respectively), despite ETGs and LTGs having stellar masses spanning across the whole range observed. The $U_{av}$ and “QPAH” fraction show no difference among different galaxy types. When fixing $U_{av}$ to the Galactic value, the derived “QPAH” fraction varies across the Galactic value (0.071). The specific SFR increases with galaxy type, while this is not the case for the dust-specific SFR (SFR/$M_{dust}$), showing an almost constant star formation efficiency per galaxy type. The galaxy sample is characterised by a tight relationship between the dust mass and the stellar mass for the LTGs and Irs, while ETGs scatter around this relation and tend towards smaller dust masses. While the relation indicates that $M_{dust}$ may fundamentally be linked to $M_\star$, metallicity and $U_{av}$ are the second parameter driving the scatter, which we investigate in a forthcoming work. We used the extended Kennicutt–Schmidt (KS) law to estimate the gas mass and the gas-to-dust mass ratio (GDR). The gas mass derived from the extended KS law is on average $\sim$20% higher than that derived from the KS law, and a large standard deviation indicates the importance of the average star formation present to regulate star formation and gas supply. The average GDR for the LTGs and Irs is 370, and including the ETGs gives an average of 550.
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Submitted on : Thursday, October 17, 2019 - 9:42:38 PM
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S. Lianou, P. Barmby, A. A. Mosenkov, M. Lehnert, O. Karczewski. Dust properties and star formation of approximately a thousand local galaxies. Astronomy and Astrophysics - A&A, EDP Sciences, 2019, 631, pp.A38. ⟨10.1051/0004-6361/201834553⟩. ⟨cea-02319402⟩

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