  We present mid/far-infrared photometry of nine FeLoBAL QSOs, taken using the
Spitzer space telescope. All nine objects are extremely bright in the infrared,
with rest-frame 1-1000 micron luminosities comparable to those of Ultraluminous
Infrared Galaxies. Furthermore, a significant fraction of the infrared emission
from many, and possibly all of the sample is likely to arise from star
formation, with star formation rates of order several hundred solar masses per
year. We combine these results with previous work to propose that FeLoBALs mark
galaxies and QSOs in which an extremely luminous starburst is approaching its
end, and in which a rapidly accreting supermassive black hole is in the last
stages of casting off its dust cocoon. FeLoBAL signatures in high redshift QSOs
and galaxies may thus be an efficient way of selecting sources at a critical
point in their evolution.

Astrophysics