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We present an analysis of the 2013 Suzaku campaign on the nearby luminousquasar PDS 456, covering a total duration of ~1 Ms and a net exposure of 455ks. During these observations, the X-ray flux was suppressed by a factor of >10in the soft X-ray band when compared to other epochs. We investigated thebroadband continuum by constructing a spectral energy distribution, making useof the optical/UV photometry and hard X-ray spectra from the laterXMM-Newton/NuSTAR campaign in 2014. The high energy part of this low flux statecannot be accounted for by self-consistent accretion disc and corona modelswithout attenuation by absorbing gas, which partially covers a substantialfraction of the line of sight towards the X-ray source. Two absorption layersare required, of column density $\log (N_{\rm{H,low}}/{\rmcm^{-2}})=22.3\pm0.1$ and $\log (N_{\rm{H,high}}/{\rm cm^{-2}})=23.2\pm0.1$,with average covering factors of ~80% (with typical 5% variations) and 60%($\pm$10-15%), respectively. In these observations PDS 456 displays significantshort term X-ray spectral variability, on timescales of ~100 ks, which can beaccounted for by variable covering of the absorbing gas. The partial coveringabsorber prefers an outflow velocity of $v_{\rm pc} = 0.25^{+0.01}_{-0.05}c$ atthe >99.9% confidence level over the case where $v_{\rm pc}=0$. This isconsistent with the velocity of the highly ionised outflow responsible for theblueshifted iron K absorption profile. We therefore suggest that the partialcovering clouds could be the denser, or clumpy part of an inhomogeneousaccretion disc wind. Finally we estimate the size-scale of the X-ray sourcefrom its variability. The radial extent of the X-ray emitter is found to be ofthe order ~15-20 $R_{\rm g}$, although the hard X-ray (>2 keV) emission mayoriginate from a more compact or patchy corona of hot electrons, which is ~6-8$R_{\rm g}$ in size.

Short term X-ray spectral variability of the quasar PDS 456 observed in a low flux state