Dust in the Circumgalactic Medium of Low-Redshift Galaxies
  Using spectroscopically selected galaxies from the Sloan Digital Sky Survey
we present a detection of reddening due to dust in the circumgalactic medium of
galaxies. We detect the mean change in the colors of "standard crayons"
correlated with the presence of foreground galaxies at z ~0.05 as a function of
angular separation. Following Peek & Graves (2010), we create standard crayons
using passively evolving galaxies corrected for Milky Way reddening and
color-redshift trends, leading to a sample with as little as 2% scatter in
color. We devise methods to ameliorate possible systematic effects related to
the estimation of colors, and we find an excess reddening induced by foreground
galaxies at a level ranging from 10 to 0.5 millimagnitudes on scales ranging
from 30 kpc to 1 Mpc. We attribute this effect to a large-scale distribution of
dust around galaxies similar to the findings of Menard et al. 2010. We find
that circumgalactic reddening is a weak function of stellar mass over the range
$6 \times 10^9 M_\odot$ -- $6 \times 10^{10} M_\odot$ and note that this
behavior appears to be consistent with recent results on the distribution of
metals in the gas phase.
