Galactic dust in the Herschel and Planck era


Francois Boulanger (Institut d’Astrophysique Spatiale)




Dust is a tracer of interstellar matter and as an agent of its physical and chemical evolution. It is much of what we see in the sky images from the Herschel and Planck space missions. The images record the emission from large dust grains with a unique combination of sky and spectral coverage, sensitivity and angular resolution, as well as with unprecedented information on polarization. From the diffuse interstellar medium to pre-stellar cores, the data trace dust evolution in the turbulent interstellar medium along the stepping-stones of star formation, from the diffuse interstellar medium to pre-stellar cores.  The observations hold great promises of answering key questions about Galactic dust. What is the impact of dust evolution on the structure and composition of interstellar dust? What are the dust emission properties at far-IR to mm wavelengths? How do they depend on interstellar environment?  How emission from large dust grains can be best used to trace interstellar matter? How well dust polarization traces the structure of the interstellar magnetic field? These questions set challenges at the heart of the interpretation of the Herschel and Planck observations. The study of Galactic dust has entered a new era, which we have just started to explore.  I will review the first results obtained from the early analysis of the data within the broader picture set by past observations. I will end discussing the prospects the data offer to move forward.