Context :

Aims : Theoretical models of wind-driven feedback from Active Galactic Nuclei ( AGN ) often identify Ultra-fast outflows ( UFOs ) as being the main cause for generating galaxy-size outflows , possibly the main actors in establishing the so-called AGN–galaxy co-evolution .
UFOs are well characterized in local AGN but much less is known in quasars at the cosmic time when SF and AGN activity peaked ( z \simeq 1 –3 ) .
It is therefore mandatory to search for evidences of UFOs in high- z sources to test the wind-driven AGN feedback models .

Methods : Here we present a study of Q2237+030 , the Einstein Cross , a quadruply-imaged radio-quiet lensed quasar located at z = 1.695 .
We performed a systematic and comprehensive temporally and spatially resolved X-ray spectral analysis of all the available Chandra and XMM- Newton data ( as of September 2019 ) .

Results : We find clear evidence for spectral variability , possibly due to absorption column density ( or covering fraction ) variability intrinsic to the source .
We detect , for the first time in this quasar , a fast X-ray wind outflowing at v _ { out } \simeq 0.1 c that would be powerful enough ( \dot { E } _ { kin } \simeq 0.1 L _ { bol } ) to significantly affect the host galaxy evolution .
We report also on the possible presence of an even faster component of the wind ( v _ { out } \sim 0.5 c ) .
Given the large sample and long time interval spanned by the analyzed X-ray data , we are able to roughly estimate , for the first time in a high- z quasar , the wind duty cycle as \approx 0.46 ( 0.31 ) at 90 % ( 95 % ) confidence level .
Finally , we also confirm the presence of a Fe K \alpha emission line with variable energy , which we discuss in the light of microlensing effects as well as considering our findings on the source .

Conclusions :