The mid-infrared and CO gas properties of an extreme star-forming
  FeLoBAL quasar
  We present a detailed study of a high-redshift iron low-ionization broad
absorption line (FeLoBAL) quasar (SDSS1214 at $z = 1.046$), including new
interferometric $^{12}$CO $J$=2-1 observations, optical through far-infrared
photometry, and mid-infrared spectroscopy. The CO line is well-fit by a single
Gaussian centered 40 kms$^{-1}$ away from the systemic velocity and implies a
total molecular gas mass of $M_\textrm{gas} = 7.3 \times 10^{10}
\textrm{M}_\odot$. The infrared SED requires three components: an active
galactic nucleus (AGN) torus, an AGN polar dust component, and a starburst. The
starburst dominates the infrared emission with a luminosity of
log($L_\textrm{SB}[\textrm{L}_\odot]) = 12.91^{+0.02}_{-0.02}$, implying a star
formation rate of about 2000 $\textrm{M}_{\odot}$yr$^{-1}$, the highest known
among FeLoBAL quasars. The AGN torus and polar dust components are less
luminous, at log($L_\textrm{AGN}[\textrm{L}_\odot]) = 12.36^{+0.14}_{-0.15}$
and log($L_\textrm{dust}[\textrm{L}_\odot]) = 11.75^{+0.26}_{-0.46}$,
respectively. If all of the molecular gas is used to fuel the ongoing star
formation, then the lower limit on the subsequent duration of the starburst is
40 Myr. We do not find conclusive evidence that the AGN is affecting the CO gas
reservoir. The properties of SDSS1214 are consistent with it representing the
endpoint of an obscured starburst transitioning through a LoBAL phase to that
of a classical quasar.
