One of the main open questions in the field of luminous (L_{\rm bol}>10^{47}\,\rm erg\,s^{-1}) quasars (QSOs) at z \gtrsim 6 is the rapid formation (< 1\,Gyr) of their supermassive black holes (SMBHs). For this work we analysed the relation between the X-ray properties and other properties describing the physics and... Show more