The physical constraints on a new LoBAL QSO at z=4.82
  Very few low-ionization broad absorption line (LoBAL) QSOs have been found at
high redshifts to date. One high-redshift LoBAL QSO, J0122+1216, was recently
discovered at the Lijiang 2.4-m Telescope with an initial redshift
determination of 4.76. Aiming to investigate its physical properties, we
carried out follow-up observations in the optical and near-IR spectroscopy.
Near-IR spectra from UKIRT and P200 confirms that it is a LoBAL, with a new
redshift determination of $4.82\pm0.01$ based on the \mgii~ emission-line. The
new \mgii~ redshift determination reveals strong blueshifts and asymmetry of
the high-ionization emission lines. We estimated a black hole mass of $\sim
2.3\times 10^9 M_\odot$ and Eddington ratio of $\sim 1.0$ according to the
empirical \mgii-based single-epoch relation and bolometric correction factor.
It is possible that strong outflows are the result of an extreme quasar
environment driven by the high Eddington ratio. A lower limit on the outflowing
kinetic power ($>0.9\% L_{Edd}$) was derived from both emission and absorption
lines, indicating these outflows play a significant role in the feedback
process to regulate the growth of its black hole as well as host galaxy
evolution.
