The origin of the distribution of stellar birth masses, known as the initial mass function (IMF), is one of the oldest unsolved problems in astrophysics. The IMF appears to be the same everywhere in the Milky Way and in nearby galaxies, but in the past few years intriguing hints have emerged that it might be slightly more bottom-heavy in cores of massive elliptical galaxies. No one knows why.
The goal of this project is to simulate the formation of star clusters including all the physics that might be relevant for the development of the IMF: turbulence, radiative feedback, protostellar outflows, and magnetic fields. These simulations will start from either conditions appropriate to the Milky Way, or those likely to have prevailed in the high-density, high-pressure star-forming environments responsible for making the stars that today lie in the densest regions of the cosmos. These simulations will use the state of the art adaptive mesh refinement radiation-MHD code ORION, and will make heavy use of large-scale supercomputing. The figure shows a series of snapshots from a previous simulation of star cluster formation done with ORION.
The simulations will permit us to explore the extent to which the difference in environment produces a difference in the mass distribution of the resulting stars. By turning on and off different pieces of physics (e.g., magnetic fields), we will be able to isolate which factors are responsible for producing the IMF we see today.