The extended High A(V) Quasar Survey: Searching for dusty absorbers
  toward mid-infrared selected quasars
  We present the results of a new spectroscopic survey for dusty intervening
absorption systems, particularly damped Ly$\alpha$ absorbers (DLAs), towards
reddened quasars. The candidate quasars are selected from mid-infrared
photometry from the Wide-field Infrared Survey Explorer combined with optical
and near-infrared photometry. Out of 1073 candidates, we secure low-resolution
spectra for 108 using the Nordic Optical Telescope on La Palma, Spain. Based on
the spectra, we are able to classify 100 of the 108 targets as quasars. A large
fraction (50 %) is observed to have broad absorption lines (BALs). Moreover, we
find 6 quasars with strange breaks in their spectra, which are not consistent
with regular dust reddening. Using template fitting we infer the amount of
reddening along each line of sight ranging from A(V)$\approx$0.1 mag to 1.2 mag
(assuming an SMC extinction curve). In four cases, the reddening is consistent
with dust exhibiting the 2175{\AA} feature caused by an intervening absorber,
and for two of these, a MgII absorption system is observed at the best-fit
absorption redshift. In the rest of the cases, the reddening is most likely
intrinsic to the quasar. We observe no evidence for dusty DLAs in this survey.
However, the large fraction of BAL quasars hampers the detection of absorption
systems. Out of the 50 non-BAL quasars only 28 have sufficiently high redshift
to detect Ly$\alpha$ in absorption.
