The Hunt for Red Quasars: Luminous Obscured Black Hole Growth Unveiled
  in the Stripe 82 X-ray Survey
  We present results of a ground-based near-infrared campaign with Palomar
TripleSpec, Keck NIRSPEC, and Gemini GNIRS to target two samples of reddened
active galactic nucleus (AGN) candidates from the 31 deg$^2$ Stripe 82 X-ray
survey. One sample, which is $\sim$89\% complete to $K<16$ (Vega), consists of
eight confirmed AGNs, four of which were identified with our follow-up program,
and is selected to have red $R-K$ colors ($>4$, Vega). The fainter sample
($K>17$, Vega) represents a pilot program to follow-up four sources from a
parent sample of 34 that are not detected in the single-epoch SDSS catalog and
have {\it WISE} quasar colors. All twelve sources are broad-line AGNs (at least
one permitted emission line has a FWHM exceeding 1300 km s$^{-1}$) and span a
redshift range $0.59 < z < 2.5$. Half the ($R-K$)-selected AGNs have features
in their spectra suggestive of outflows. When comparing these sources to a
matched sample of blue Type 1 AGNs, we find the reddened AGNs are more distant
($z > 0.5$) and a greater percentage have high X-ray luminosities ($L_{\rm
X,full} > 10^{44}$ erg s$^{-1}$). Such outflows and high luminosities may be
consistent with the paradigm that reddened broad-line AGNs represent a
transitory phase in AGN evolution as described by the major merger model for
black hole growth. Results from our pilot program demonstrate proof-of-concept
that our selection technique is successful in discovering reddened quasars at
$z > 1$ missed by optical surveys.
