Collapse of massive magnetized dense cores using radiation magnetohydrodynamics: early fragmentation inhibition Benoit Commerçon LERMA - ENS Paris, Paris, France
We report the results of radiation-magnetohydrodynamics calculations in the context of high-mass star formation, using for the first time a self-consistent model for photon emission (i.e., via thermal emission and in radiative shocks) and with the high resolution necessary to properly resolve magnetic braking effects and radiative shocks on scales <100 AU. We investigate the combined effects of magnetic field, turbulence, and radiative transfer on the early phases of the collapse and the fragmentation of massive dense cores. We identify a new mechanism that inhibits initial fragmentation of massive dense cores where magnetic field and radiative transfer interplay. We show that this interplay becomes stronger as the magnetic field strength increases. Magnetic braking is transporting angular momentum outward and is lowering the rotational support and is thus increasing the infall velocity. This enhances the radiative feedback owing to the accretion shock on the first core. We speculate that highly magnetized massive dense cores are good candidates for isolated massive star formation while moderately magnetized massive dense cores are more appropriate forming OB associations or small star clusters. Finally, we will present synthetic observations of these collapsing massive dense cores.
Caption: Top: column density maps of collapsing massive dense cores integrated in the y-direction for four models: SPHYDRO at time ∼t0 + 2.6 kyr, MU130 at time ∼t0 + 25.4 kyr, MU5 at time ∼t0 + 7.5 kyr, and MU2 at time ∼t0 + 7.3 kyr. Bottom: local Jeans length and velocity field cut in the xz-plane for the same calculations and at the same time as in the upper row.
Collaborators: P. Hennebelle, LERMA - ENS Paris, France Th. Henning, MPIA Heidelberg, Germany	Key publication