Cool Customers in the Stellar Graveyard. III. Limits to Substellar Objects around nearby White Dwarfs using the Canada-France-Hawaii Telescope

Results from a groundbased high contrast imaging survey of thirteen nearbywhite dwarfs for substellar objects is presented. We place strict upper limitson the type of substellar objects present, ruling out the presence of anythinglarger than $\sim$14 M$_{Jup}$ for eight of the white dwarfs at separations$>$19 AU and corresponding to primordial separations of $\sim$3-6~AU assumingadiabatic mass loss without tidal interactions. With these results we place the first upper limit on the number ofintermediate mass stars with brown dwarfs at separations $>$ 13 AU. We combinethese results with previous work to place upper limits on the number of massiveJovian ($>$ 10 M$_{Jup}$) planets in orbit around white dwarfs whoseprogenitors spanned a mass range of 1-7 M$_{\odot}$.Comment: 20 pages, 6 figures, Accepted to AJ, minor edit