The Initial Mass Function and Birth History of Brown Dwarfs in the Solar Neighborhood from a Volume-Limited Sample

As the lowest-mass products of star formation, brown dwarfs are essential to understanding the history of our galaxy. To this end, a complete volume-limited sample of brown dwarfs in the solar neighborhood is critical for testing formation theories. To create such a sample, our Hawaii Infrared Parallax Program has recently measured parallaxes for 350 L and T dwarfs, the largest single batch of parallaxes for brown dwarfs to date. Using our work and literature measurements, we have constructed a volume-limited sample of brown dwarfs out to 25 pc. We augmented this with a large Keck adaptive-optics imaging campaign to establish the binary properties of the sample. We use population synthesis analysis to establish the initial mass function and birth history of substellar objects in the Solar neighborhood.  We compare with IMF measurements for the solar neighborhood.