  We report the detection of redshifted iron K-alpha absorption lines in the
Chandra LETG spectrum of the narrow-line quasar, PG 1211+143. The absorption
lines are observed at 4.22 keV and 4.93 keV in the quasar spectrum,
corresponding to 4.56 keV and 5.33 keV in the rest frame of PG 1211+143. From
Monte Carlo simulations, the chance probability of both lines being false
detections is low at 1.36e-04. Highly redshifted ionized iron K-alpha (Fe XXV
or Fe XXVI) is the most plausible identification for the lines at their
observed energies. If identified with H-like iron K-alpha at 6.97 keV, then the
relativistic velocity shifts required are 0.40c and 0.26c. The extreme
velocities can be explained by pure gravitational redshift if the matter exists
in a stable orbit within 6 gravitational radii of the black hole. This would
require a Kerr metric for the black hole. Alternatively the absorption may be
the result of matter infalling directly onto the black hole, with a maximum
observed velocity of 0.38c at 6Rg in the Schwarzschild metric. This matter may
originate in a failed outflow or jet, which does not escape the gravitational
potential of the black hole.
