The early phase of star formation : polarization properties of galactic cold cores and filaments

Student : Jean-Sébastien CARRIÈRE

Advisors : Isabelle RISTORCELLI, Ludovic MONTIER, Katia FERRIERE

Start : Octobre 2018

Group : MICMAC

The physical mechanisms regulating star formation still remain poorly understood. Different processes are involved (gravity, turbulence, magnetic field, radiative pressure), but their actual roles and interplay has to be investigated. For this purpose, different scales must be probed, from molecular clouds to filaments, cold clumps and prestellar cores. Planck and Herschel satellites have recently brought new insights on the cold Galactic component. The surveys have revealed that filamentary structures are ubiquitous in the diffuse ISM and in star-forming molecular clouds. Thousands of dense cores have been detected, and the prestellar cores are preferentially located in the densest filaments. The question on the origin and evolution of dense cores is now strongly connected to the filaments.The objectives of the PhD thesis are to study the properties of the magnetic field toward the cold cores and clumps detected with Planck-Herchel and toward their environment structures (filaments). This analysis will be based on the observations of the dust polarized emission using surveys offering complementary angular resolutions in order to probe the magnetic field over a large range of spatial scales (ground-based telescopes : SMA, NIKA2, SCUBA-pol, ALMA, or space telescopes: Planck and PILOT). These measurements will be used to study the relative orientation between the magnetic field and the structures (filaments and cores)and analyse the variation of the polarization fraction. These characteristics will be studied in relation with the physical properties of the cold cores and their evolutionary degrees. They will be also compared to predictions from numerical MHD simulations.