A Massive X-Ray Outflow from the Quasar PDS 456

We report on XMM-Newton spectroscopic observations of the luminous,radio-quiet quasar PDS 456. The hard X-ray spectrum of PDS 456 shows a deepabsorption trough (constituting 50% of the continuum) at energies above 7 keVin the quasar rest frame, which can be attributed to a series of blue-shiftedK-shell absorption edges due to highly ionized iron. The higher resolution softX-ray RGS spectrum exhibits a broad absorption line feature near 1 keV, whichcan be modeled by a blend of L-shell transitions from highly ionized iron (FeXVII-XXIV). An extreme outflow velocity of 50000 km/s is required to model theK and L shell iron absorption present in the XMM-Newton data. Overall, a largecolumn density ($N_{H}=5\times10^{23}$cm$^{-2}$) of highly ionized gas(logxi=2.5) is required in PDS 456. A high mass outflow rate of 10 solar massesper year (assuming a conservative outflow covering factor of 0.1 steradian) isderived, which is of the same order as the overall mass accretion rate in PDS456. The kinetic energy of the outflow represents a substantial fraction (10%)of the quasar energy budget, whilst the large column and outflow velocity placePDS 456 towards the extreme end of the broad absorption line quasar population.Comment: 13 pages, 3 figures. Accepted for publication in ApJ Letter