Multi-Physics, Multi-Scale Simulations of Star Formation: A Hierarchical Approach from Large Scale Turbulent Magnetized Clouds to Stellar Clusters

Date: 
Wednesday, May 11, 2016 - 3:30pm to 4:30pm PDT
Speaker: 
Richard Klein
Affiliation: 
UC Berkeley
Location: 
N232, Room 103
Event Type: 
Colloquium

The origin and formation of stellar clusters remains a fundamental grand challenge in astrophysics that requires complex multi-physics simulations that must include a large range of coupled physical processes, including: self-gravity; supersonic turbulence; hydrodynamics; outflows; radiation and magnetic fields. I shall present new simulations that for the first time investigate star formation with the above fully coupled multi-physics that include feedback from protostellar outflows and radiative transfer traversing the large scales of magnetized turbulent clouds down to the micro-scales of protostars and clusters using a hierarchical zoom-in AMR approach with our 3D adaptive mesh refinement (AMR) code, ORION2. These simulations follow the gravitational collapse of a magnetized, supersonically turbulent, massive molecular cloud through to the formation of dense IRDC filaments, multiple turbulent clumps inside these IRDCs and the evolution of magnetized cores.  Filamentary structure emerges naturally from our simulations. Magnetic field lines pierce the dark cloud filament primarily in the direction normal to the filament axis. We have carried out the most detailed analysis to date of the magnetic field properties of the cloud clumps in our simulations (Li, McKee and Klein, 2015), finding excellent agreement with the Zeeman observations of Crutcher et al. (2010). We perform deep zoom-in simulations into the structure of the main IRDC filament to study the formation and properties of a stellar cluster inside IRDCs. I shall discuss the effects of both radiative feedback and protostellar outflow feedback from the protocluster on the surrounding environs and (1) the formation of the resultant IMF and its agreement with the Chabrier IMF, (2) the Protostellar Mass function and the Proto-stellar Luminosity function and make detailed comparisons with several theoretical models and with observations, (3) the multiplicity fractions within the cluster and comparisons with observations of Class I protostars, (4) the cluster luminosity and comparisons with observations and finally, (5) the comparison of our proto-stellar outflows with theoretical models and recent observations. We find that the star formation efficiency is super-linear in time resulting in a star formation rate that is in good agreement with recent observations.

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