  Active galactic nucleus (AGN) feedback is the process by which supermassive
black holes in the centres of galaxies may moderate the growth of their hosts.
Gas outflows from supermassive black holes release huge quantities of energy
into the interstellar medium, clearing the surrounding gas. The most extreme of
these, the ultra-fast outflows (UFOs), are the subset of X-ray detected
outflows with velocities higher than 10,000 km/s, believed to originate in
relativistic disc winds, a few hundred gravitational radii from the black hole.
The absorption features produced by these outflows are variable, but no clear
link has been found between the behaviour of the X-ray continuum and the energy
or equivalent width of the outflow features due to the long time-scales of
quasar variability. Here, we present the detection of multiple absorption lines
from an extreme ultra-fast gas flow in the X-ray spectrum of the active
galactic nucleus IRAS 13224-3809, at 0.236+/-0.006 times the speed of light
(71,000 km/s), where the absorption is strongly anti-correlated with the
emission from the inner regions of the accretion disk. If the gas flow is
identified as a genuine outflow then it is in the fastest 5 per cent of such
winds, and its variability is hundreds of times faster than in other variable
winds, allowing us to observe in hours what would take months in a quasar. We
find signatures of the wind simultaneously in both low and high energy
detectors, which are consistent with a single ionized outflow, linking the two
phenomena. The detection of the wind responding to the emission from the inner
disk demonstrates a connection between accretion processes occurring on very
different scales, with the X-rays from within a few gravitational radii of the
black hole ionizing the relativistically outflowing gas as the flux rises.
