The Discovery of Gas-Rich, Dusty Starbursts in Luminous Reddened Quasars
  at $z\sim2.5$ with ALMA
  We present ALMA observations of cold dust and molecular gas in four
high-luminosity, heavily reddened (A$_{\rm{V}} \sim 2.5-6$ mag) Type 1 quasars
at $z\sim2.5$ with virial M$_{\rm{BH}} \sim 10^{10}$M$_\odot$, to test whether
dusty, massive quasars represent the evolutionary link between submillimetre
bright galaxies (SMGs) and unobscured quasars. All four quasars are detected in
both the dust continuum and in the $^{12}$CO(3-2) line. The mean dust mass is
6$\times$10$^{8}$M$_\odot$ assuming a typical high redshift quasar spectral
energy distribution (T=41K, $\beta$=1.95 or T=47K, $\beta$=1.6). The implied
star formation rates are very high - $\gtrsim$1000 M$_\odot$ yr$^{-1}$ in all
cases. Gas masses estimated from the CO line luminosities cover
$\sim$1-5$\times10^{10}$($\alpha_{\rm{CO}} / 0.8$)M$_\odot$ and the gas
depletion timescales are very short - $\sim5-20$Myr. A range of gas-to-dust
ratios is observed in the sample. We resolve the molecular gas in one quasar -
ULASJ2315$+$0143 ($z=2.561$) - which shows a strong velocity gradient over
$\sim$20 kpc. The velocity field is consistent with a rotationally supported
gas disk but other scenarios, e.g. mergers, cannot be ruled out at the current
resolution of these data. In another quasar - ULASJ1234+0907 ($z=2.503$) - we
detected molecular line emission from two millimetre bright galaxies within 200
kpc of the quasar, suggesting that this quasar resides in a significant
over-density. The high detection rate of both cold dust and molecular gas in
these sources, suggests that reddened quasars could correspond to an early
phase in massive galaxy formation associated with large gas reservoirs and
significant star formation.
