Expanding the Census of L/T Transition Brown Dwarfs with the Pan-STARRS and WISE Surveys

We have searched 30,000 deg₂ in the Pan-STARRS 1 (PS1) 3π and WISE all-sky surveys for brown dwarfs in the L/T transition (spectral types ≈ L6-T3.5). These objects exhibit drastic spectral changes over a narrow temperature range (≈ 1300-900 K), effects which are challenging for models to reproduce. Previous large-scale searches have been incomplete for L/T transition dwarfs because these objects are faint in optical bands and have near-infrared colors that are difficult to distinguish from background stars. To overcome these obstacles, we have cross-matched the PS1 (optical) and WISE (mid-IR) catalogs to produce a unique multi-wavelength database for finding ultracool dwarfs. We have obtained near-infrared spectra for 13 candidates and confirmed that 12 are new L/T transition dwarfs. Given our initial success rate, this search has the potential to identify hundreds of new L/T transition dwarfs. The search will fill a known gap in the solar neighborhood census, and significantly improve the constraints on the local substellar mass and luminosity functions. We expect to identify a well-defined, volume-limited sample of dozens of late L and early T dwarfs, which will be used to better understand and model the evolution of brown dwarfs through the L/T transition.