The role of magnetic braking in regulating gravitational collapse and circumstellar disk during the main accretion phase, is an open question. While only indirect evidence was found from observational work, such as compact disk sizes and the launching of high-velocity collimated jets, we aim at more direct tests of the magnetic braking in observations. The study of polarized dust emission as a tracer of the magnetic field and molecular line emission as a tracer of gas kinematics in young protostars can provide valuable information for understanding how the presence of the magnetic field affects the accretion process.
In the present work, we have used both non-ideal MHD models and synthetic observations from the radiative transfer of protostellar formation to put constraints on the magnetically-regulated disk formation scenario. We use our model synthetic observations to identify possible direct signatures of the magnetic braking from the maps of the molecular gas emission. By comparing the specific angular momentum of two similar models that differ in magnetic flux, we see that the more magnetized model shows a higher angular momentum redistribution above 1000 au. In addition, we have tested the methods typically used to infer the specific angular momentum from an observational point of view. We have found possible observational evidence of magnetic braking in the kinematics of the C18O (2-1) molecule, such as a flattening of the radial profile of specific angular momentum for radii smaller than 1000 au for the more magnetized model similar to the characteristics found in observational work. On the other hand, in this study we show that the maximum velocity computed in the equatorial plane, which is traditionally used as an approximation of the rotational velocity, may overestimate the rotational velocity, probably due to contamination from radial motions.
Contact local : Thierry FOGLIZZO
Organisateur : Frédéric GALLIANO
