Dusty WDs in the $WISE$ All Sky Survey $\cap$ SDSS
  A recent cross-correlation between the SDSS DR7 White Dwarf Catalog with the
Wide-Field Infrared Survey Explorer ($WISE$) all-sky photometry at 3.4, 4.6,
12, and 22 microns performed by Debes et al. (2011) resulted in the discovery
of 52 candidate dusty white dwarfs (WDs). The 6'' $WISE$ beam allows for the
possibility that many of the excesses exhibited by these WDs may be due to
contamination from a nearby source, however. We present MMT$+$SWIRC $J$- and
$H$-band imaging observations (0.5-1.5'' PSF) of 16 of these candidate dusty
WDs and confirm that four have spectral energy distributions (SEDs) consistent
with a dusty disk and are not accompanied by a nearby source contaminant. The
remaining 12 WDs have contaminated $WISE$ photometry and SEDs inconsistent with
a dusty disk when the contaminating sources are not included in the photometry
measurements. We find the frequency of disks around single WDs in the $WISE$
$\cap$ SDSS sample to be 2.6-4.1%. One of the four new dusty WDs has a mass of
$1.04 M_{\odot}$ (progenitor mass $5.4 M_{\odot}$) and its discovery offers the
first confirmation that massive WDs (and their massive progenitor stars) host
planetary systems.
