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Past X-ray observations of the nearby luminous quasar PDS 456 (at $z=0.184$)have revealed a wide angle accretion disk wind (Nardini et al. 2015), with anoutflow velocity of $\sim-0.25c$, as observed through observations of itsblue-shifted iron K-shell absorption line profile. Here we present three newXMM-Newton observations of PDS 456; one in September 2018 where the quasar wasbright and featureless, and two in September 2019, 22 days apart, occurringwhen the quasar was five times fainter and where strong blue-shifted lines fromthe wind were present. During the second September 2019 observation, threebroad ($\sigma=3000$ km s$^{-1}$) absorption lines were resolved in the highresolution RGS spectrum, which are identified with blue-shifted OVIIILy$\alpha$, NeIX He$\alpha$ and NeX Ly$\alpha$. The outflow velocity of thissoft X-ray absorber was found to be $v/c=-0.258\pm0.003$, fully consistent withiron K absorber with $v/c=-0.261\pm0.007$. The ionization parameter and columndensity of the soft X-ray component ($\log\xi=3.4$, $N_{\rm H}=2\times10^{21}$cm$^{-2}$) outflow was lower by about two orders of magnitude, when compared tothe high ionization wind at iron K ($\log\xi=5$, $N_{\rm H}=7\times10^{23}$cm$^{-2}$). Substantial variability was seen in the soft X-ray absorber betweenthe 2019 observations, declining from $N_{\rm H}=10^{23}$ cm$^{-2}$ to $N_{\rmH}=10^{21}$ cm$^{-2}$ over 20 days, while the iron K component was remarkablystable. We conclude that the soft X-ray wind may originate from aninhomogeneous wind streamline passing across the line of sight and which due toits lower ionization, is located further from the black hole, on parsec scales,than the innermost disk wind.

Resolving the soft X-ray ultra fast outflow in PDS 456