Past X-ray observations of the nearby luminous quasar PDS 456 ( at z = 0.184 ) have revealed a wide angle accretion disk wind ( 20 ) , with an outflow velocity of \sim - 0.25 c .
Here we unveil a new , relativistic component of the wind through hard X-ray observations with NuSTAR and XMM-Newton , obtained in March 2017 when the quasar was in a low flux state .
This very fast wind component , with an outflow velocity of -0.46 \pm 0.02 c , is detected in the iron K band , in addition to the -0.25 c wind zone .
The relativistic component may arise from the innermost disk wind , launched from close to the black hole at radius of \sim 10 gravitational radii .
The opacity of the fast wind also increases during a possible obscuration event lasting for 50 ks .
We suggest that the very fast wind may only be apparent during the lowest X-ray flux states of PDS 456 , becoming overly ionized as the luminosity increases .
Overall , the total wind power may even approach the Eddington value .