Abstract:

The interstellar medium plays a central role in the evolution of galaxies, as it serves as the fuel for star formation. Its structure and composition also informs us about the past history of star formation. Its observation has made tremendous progress over the past 30 years, thanks to airborne,ground-based and satellite observations.Most recently, the advent of the Herschel Space Observatory and of the Planck satellite has fully opened the FIR-mm observation window where the interstellar medium can be best studied.I will review some of the recent results related to the physics of dust and gas in our galaxy and nearby galaxies.These results have shown that dust emission can be used to accurately probe the whole molecular gas from which stars form, which remained difficult using more conventional molecular tracers. They also indicated that dust emission is more complex than previously anticipated, showing variations with environment. The possible reasons for that, such as the presence of spinning small dust particles, the mechanical structure of dust grains or the aggregation of dust particles will be discussed. I will also discuss the future prospect of using polarization measurements to further constrain the nature of dust and the geometry of the magnetic field, which is likely to play a central role for star formation.These themes are important to our understanding of the interstellar medium in galaxies, but also to the efficient removal of galactic foreground emission for future cosmology observations of the Cosmic Microwave Background.