X-ray spectroscopy and variability of the luminous quasar PDS 456

In this thesis I present contemporary X-ray observations of the “Rosetta Stone” of black hole winds, the luminous quasar PDS 456. I perform a detailed analysis of a recent, long Suzaku campaign in 2013 (of ~ 1 Ms duration) where the X-ray flux was unusually low. During this campaign PDS 456 displays significant short-term X-ray spectral variability, on time-scales of ~ 100 ks, due to variable absorbing gas crossing the line-of-sight. By investigating the physical properties of these X-ray absorbers I find that they constitute the same inhomogeneous ultra fast accretion disc-wind (vw ~ 0:25c), which is characterized by highly ionized gas, relatively close to the SMBH and colder, denser clumpy material located further out.A series of five simultaneous observations of PDS 456 with XMM-Newton & NuSTAR then resolved the P-Cygni like profile at Fe K, confirming that the absorption originates from a fast (vmax = 0:35+_0:02c), wide angle (i.e., & 2p) wind, capable of causing significant feedback between the black hole and its host galaxy. Collating all the Suzaku and XMM-Newton & NuSTAR observations from 2007–2014, I show that the wind velocity appears correlated with the X-ray luminosity, which may imply that the wind is radiatively driven.The last part of the project is focused on the broadband analysis of PDS456 from the 2007 archival Suzaku data (~ 370 ks in duration), where the quasar was observed in a high-flux state and the unabsorbed AGN primary continuum was revealed. Significant spectral variability is present during the intrinsic X-ray flares that are present in this observation, which are likely driven by fluctuations in a two-component (accretion disc plus corona) continuum. This takes the form of a variable soft X-ray excess (< 1 keV), likely to be the Comptonized tail of the accretion disc emission, as well as a high energy powerlaw. The X-ray emission in PDS 456 appears to originate from two distinct regions:- (i) a warm, optically thick layer of gas blanketing the disc, which is responsible for the soft X-ray excess and (ii) a hot/thin electron corona above the disc, which produces the hard X-ray emission. The latter is typically 10Rg in extent and appears to be Compton cooled by soft X-ray emission