Title:  Constraining Brown Dwarf Formation and Evolution in the Solar Neighborhood

Abstract:  As the extreme lowest-mass products of star formation, brown dwarfs are essential to understanding the star formation 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, we have measured parallaxes for 348 L and T dwarfs using the wide-field infrared camera WFCAM on UKIRT to reach well beyond the limits of Gaia, producing the largest single batch of parallaxes for brown dwarfs to date and complementing other recent parallax programs targeting young or very late-type brown dwarfs.  We constructed a volume-limited sample of L0-T8 dwarfs out to 25 pc, covering two-thirds of the sky and ~90% complete. I will discuss what this sample is teaching us about how brown dwarfs cool as they age, and how we are placing new constraints on the substellar initial mass function and age distribution in the Solar Neighborhood.