Title: Resolved dust-to-gas mass ratio in nearby galaxies
The relation between the dust-to-gas ratio (DGR) and metallicity provides an important tool to study the evolutionary stage of a galaxy as it links the amount of metals bound in dust and in the gas phase. It allows to put constraints on dust evolution models which predict the balance between dust formation, growth and destruction and the total amount of metals. On the other hand, dust evolution models depend strongly on a precise estimate of the dust mass and the mass of molecular gas.
For my study, we implemented a hierarchical bayesian technique to derive the dust mass fitting the far-IR spectral energy distribution, which break the known degeneracy between dust temperature and emissivity index.
I used a sample of 29 galaxies selected from the SINGS (Spitzer), KINGFISH (Herschel) and HERACLES (IRAM 30 m) and THINGS (VLA) surveys to study the relations between DGR and other ISM parameters, like the stellar mass, dust temperatures, star formation rate and metallicity. This kind of study of nearby galaxies allows us to resolved their internal structure and analyze how these quantities distribute within the individual galaxies.
In this talk, I am going to present the radial profiles of different ISM parameters, the influence of the CO-to-H2 conversion factor (co), the advantages of our new method to derived the dust masses of nearby galaxies and their impact on the determination of the DGR. Finally, I will discuss the DGR-metallicity relation and how these results fit in the general picture of nearby galaxies.