FIRST-2MASS Red Quasars: Transitional Objects Emerging from the Dust
  We present a sample of 120 dust-reddened quasars identified by matching radio
sources detected at 1.4 GHz in the FIRST survey with the near-infrared 2MASS
catalog and color-selecting red sources. Optical and/or near-infrared
spectroscopy provide broad wavelength sampling of their spectral energy
distributions that we use to determine their reddening, characterized by
E(B-V). We demonstrate that the reddening in these quasars is best-described by
SMC-like dust. This sample spans a wide range in redshift and reddening (0.1 <
z < 3, 0.1 < E(B-V) < 1.5), which we use to investigate the possible
correlation of luminosity with reddening. At every redshift, dust-reddened
quasars are intrinsically the most luminous quasars. We interpret this result
in the context of merger-driven quasar/galaxy co-evolution where these reddened
quasars are revealing an emergent phase during which the heavily obscured
quasar is shedding its cocoon of dust prior to becoming a "normal" blue quasar.
When correcting for extinction, we find that, depending on how the parent
population is defined, these red quasars make up < 15-20% of the luminous
quasar population. We estimate, based on the fraction of objects in this phase,
that its duration is 15-20% as long as the unobscured, blue quasar phase.
